# Dwyer CO2 flow rate-Model rma150-ssv



## Grobbins48 (Oct 16, 2017)

houstonreef said:


> Does anyone know what ports on the Dwyer for input and output? There is a port behind the control knob and another one is at the top of the device.
> 
> Thanks in advance


150 or 151?


Are you looking for the thread size of the input and output? 


My 151 I believe are 1/8NPT. 


Check this post for all my detsils, but the 1/8 NPT should be right.

https://www.plantedtank.net/forums/showthread.php?p=10948121


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## Mike A. (Jan 6, 2018)

Just finished setting one up. Definitely 1/8" female NPT for both. Bottom in, top out.

If you see it bouncing around some, then you likely have a leak somewhere. Likewise, if the flow measure seems high relative to what you're seeing as the output as you up the pressure, then you likely have a leak. Just a tiny, slow leak makes a big difference given the scale of these.


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## houstonreef (Aug 24, 2018)

Thanks all for the advice. I connected it correctly bottom in and top out. I accidentally let some mineral oil into the flow rate. I am not sure it affect the performance nor not.


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## KayakJimW (Aug 12, 2016)

I'm about to pull the trigger on the RMA-151-SSV, do y'all use plumber's tape on the threads or a donut gasket?

Also I feel like SSV would be superior but found it interesting that the brass metering valve version is more expensive on both 150 and 151 models... 

what's your preferred metal for the 1/8 npt to hose barb adapter?


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## OVT (Nov 29, 2011)

Where do you buy them? I don't see these models on Amazon.
Thanks!


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## Ken Keating1 (Nov 22, 2017)

OVT said:


> Where do you buy them? I don't see these models on Amazon.
> Thanks!


You can purchase them direct from Dwyer *here.* I bought one direct from them as I couldn't find one on Amazon.


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## Mike A. (Jan 6, 2018)

OVT said:


> Where do you buy them? I don't see these models on Amazon.
> Thanks!


https://www.amazon.com/Dwyer-Rate-Master-Flowmeter-Female-Connections/dp/B009PACIGA

Picture is wrong, it's the front valve. Last week they had some with the brass valve for $40 but they're back up higher than the stainless now. Ordering from Dwyer is about $1 less as now priced.


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## Grobbins48 (Oct 16, 2017)

OVT said:


> Where do you buy them? I don't see these models on Amazon.
> 
> Thanks!


I used everyone favorite auction site. Bought a used one and a new one, both work well.


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## Grobbins48 (Oct 16, 2017)

KayakJimW said:


> I'm about to pull the trigger on the RMA-151-SSV, do y'all use plumber's tape on the threads or a donut gasket?
> 
> 
> 
> ...


I did use tape when putting the 1/8npt barbs on. Wrap it a few times I the right direction and you are good to go. I believe it is a brass barb adapter. Had to purchase them online- lowes or home depot will not have that size. 

I may have used clippard actually, as I also made some check valves from them too.


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## Greggz (May 19, 2008)

Ken Keating1 said:


> You can purchase them direct from Dwyer *here.* I bought one direct from them as I couldn't find one on Amazon.


Yes you can go right to the source.

When you get to the page, look to the left at the "filter by" section. Check the box next to "2" Scale (RMA) with Stainless Steel Valve" then scroll down and click on "filter". 

I mention it as I have seen some post that they bought one with no valve by mistake.

You need to purchase the adapters. They will look something like this............................










You will want 1/8 NPT 3/16 ID Hose barb. Yes, doesn't seem right as hole seems bigger than 1/8", but you have to understand the way NPT (national pipe thread) works. A 1/8" NPT thread is actually .405" OD. Might find it locally but most likely need to order on line.

Also comes in elbow version if that works better for your set up.

And you do need to use teflon tape. If you try to screw it in dry, it will not seem to fit. Goes in smooth with teflon tape, as that is how the thread is designed to work.


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## OVT (Nov 29, 2011)

Thank you all for the replies.
My plan is to use it with a needle valve and I might get the model without one for a ~120g tank. The 10-100 cc/min versions all seem to come with a build in valve though.


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## houstonreef (Aug 24, 2018)

Greggz, my model RMS 150 SSV is right for my tank , 115g?

I order my at global supply and the adapter at ACE. Home Depot and Lowe’s don’t have it at my area.


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## jeffkrol (Jun 5, 2013)

Greggz said:


> And you do need to use teflon tape. If you try to screw it in dry, it will not seem to fit. Goes in smooth with teflon tape, as that is how the thread is designed to work.



Trying to avoid splitting hairs.. 

Bump:


OVT said:


> Thank you all for the replies.
> My plan is to use it with a needle valve and I might get the model without one for a ~120g tank. The 10-100 cc/min versions all seem to come with a build in valve though.


 https://www.radwell.com/Shop?source...MI8d6ag7L63wIVoP7jBx18jAGOEAkYASABEgLdYPD_BwE


Try them.. Should be able to get one somewhere .. Question is is it cheaper?...




> RMA-150 Flowmeter, range 10-100 cc/min air, no valve. ±8% accuracy.


https://www.dwyer-inst.com/Product/Flow/Flowmeters/VariableArea/SeriesRM


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## Greggz (May 19, 2008)

houstonreef said:


> Greggz, my model RMS 150 SSV is right for my tank , 115g?
> 
> I order my at global supply and the adapter at ACE. Home Depot and Lowe’s don’t have it at my area.


Yeah that would be my choice. You will probably be between 40 & 60 cc/min, so better to err with more scale (RMS 150 10-100 cc/min vs RMS 151 5-50 cc/min scale).


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## houstonreef (Aug 24, 2018)

By the way, anyone can recommend a reliable CO2 check valve.


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## Cichlid-140 (Sep 28, 2018)

Greggz said:


> Yeah that would be my choice. You will probably be between 40 & 60 cc/min, so better to err with more scale (RMS 150 10-100 cc/min vs RMS 151 5-50 cc/min scale).


I need to recheck my pH drop. I'm only running 10cc/min into a 155G water column and at my last check that gave me a ~1.00 drop. Everything I've read says that's low.

I'm using a GLA inline diffuser and passing it through ~20 feet of 5/8 inch ID hose then into the return chamber of my sump directly toward the inlet of the return pump.

20181222_170056 by pat w1, on Flickr

The pic shows ~13-14cc/min. I know. It's a solid 10 now. I've got a new sample in the garage degassing now. Odd.


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## Edward (Apr 11, 2005)

Cichlid-140 said:


> I'm only running 10cc/min into a 155G water column and at my last check that gave me a ~1.00 drop. Everything I've read says that's low.


 Running 15 ccm / 2 bps on 125 gallon gives me 1.7 pH drop.


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## Grobbins48 (Oct 16, 2017)

Cichlid-140 said:


> I need to recheck my pH drop. I'm only running 10cc/min into a 155G water column and at my last check that gave me a ~1.00 drop. Everything I've read says that's low.
> 
> I'm using a GLA inline diffuser and passing it through ~20 feet of 5/8 inch ID hose then into the return chamber of my sump directly toward the inlet of the return pump.
> 
> ...



Very interesting- I'll be curious to see what you get measuring again.



Edward said:


> Running 15 ccm / 2 bps on 125 gallon gives me 1.7 pH drop.


What type of diffusion method are you using for this? Do you have very low surface agitation? I am very curious on these two relatively low cc/min readings. On my 55 I run around 20-25cc/min for a 1.45ish drop. I have high surface agitation, but the delta between our readings is massive when taking our tank volumes into account.

EDIT: I am running ~40PSI into a 10 inch cerges reactor.


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## Cichlid-140 (Sep 28, 2018)

Edward said:


> Running 15 ccm / 2 bps on 125 gallon gives me 1.7 pH drop.


10 cc/min for me - bubble counting is a waste of time, way too fast. What pressure are you running. I've got mine at 44psi.

Bump:


Grobbins48 said:


> Very interesting- I'll be curious to see what you get measuring again.
> 
> 
> 
> What type of diffusion method are you using for this? Do you have very low surface agitation? I am very curious on these two relatively low cc/min readings. On my 55 I run around 20-25cc/min for a 1.45ish drop. I have high surface agitation, but the delta between our readings is massive when taking our tank volumes into account.


Surface agitation is pretty high and add to that I run a sump with a surface skimming overflow weir and 4 large baffles in the sump itself. Loads of gas transfer.

The inline diffuser runs directly through 20' of tubing, like I said. It acts like a dwell time reactor but I still get a fair amount of mist in the tank. Not obnoxious but noticeable.


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## Greggz (May 19, 2008)

Cichlid-140 said:


> I need to recheck my pH drop. I'm only running 10cc/min into a 155G water column and at my last check that gave me a ~1.00 drop. Everything I've read says that's low.
> 
> I'm using a GLA inline diffuser and passing it through ~20 feet of 5/8 inch ID hose then into the return chamber of my sump directly toward the inlet of the return pump.
> 
> ...


Something seems off. 

That's only based on the many folks who have posted their flow rate, tank size, and pH drop.

I'll be interested to see where this goes. Who knows, I might be missing something.

Bump:


Edward said:


> Running 15 ccm / 2 bps on 125 gallon gives me 1.7 pH drop.


Guessing no fish or surface agitation?

And 15 cm/min = about 6 to 8 BPS on my system. But lots of variables, so who knows. 

Most important thing to me is always measuring relative values. So if a setting grows plants better, absolute value is meaningless.


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## Ken Keating1 (Nov 22, 2017)

The Dwyer flow meters indicate correct flow only at 0 PSI and 70 degrees Fahrenheit. At other temps or pressures you have to calculate with a formula to determine the corrected flow rate. The pressure and temps need to be taken at the output of the flow meter. The formula and example can be found *here.* Since none of us, at least not yet or not that I'm aware of have a pressure gauge on the output of the flow meter we can't really compare readings until we do this and apply the correction formula.

It others would like to start adding pressure gauges to the flow meter output to make comparisons, I'm game and would do this in the interest to see if there are some similarities between tanks.


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## Ken Keating1 (Nov 22, 2017)

I've snipped the formula's from the pdf link I provided above:


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## Edward (Apr 11, 2005)

Grobbins48 said:


> What type of diffusion method are you using for this? Do you have very low surface agitation? I am very curious on these two relatively low cc/min readings. On my 55 I run around 20-25cc/min for a 1.45ish drop. I have high surface agitation, but the delta between our readings is massive when taking our tank volumes into account. EDIT: I am running ~40PSI into a 10 inch cerges reactor.


 AquaMedic CO2 Reactor 1000, and aeration is done by two air pumps with two large double sponge filters with 90° outlets. 



Ken Keating1 said:


> It others would like to start adding pressure gauges to the flow meter output to make comparisons, I'm game and would do this in the interest to see if there are some similarities between tanks.


 The outlet pressure is more less created by the depth of the flow meter in relation to the aquarium water level, usually 2 to 3 feet. And the list is here https://www.plantedtank.net/forums/...our-setting-cc-min-gallon-3.html#post11084997



Cichlid-140 said:


> 10 cc/min for me - bubble counting is a waste of time, way too fast. What pressure are you running. I've got mine at 44psi.


 We can count the bubbles for maybe for 20 to 30 seconds with a timer and then calculate the exact rate. What incoming pressure? It is 18 psi, because that’s the right pressure for the beer kegs.


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## AguaScape (Oct 28, 2018)

OVT said:


> Where do you buy them? I don't see these models on Amazon.
> Thanks!


I got you covered @OVT. Check your PM's


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## Ken Keating1 (Nov 22, 2017)

Edward said:


> The outlet pressure is more less created by the depth of the flow meter in relation to the aquarium water level, usually 2 to 3 feet. And the list is here https://www.plantedtank.net/forums/...our-setting-cc-min-gallon-3.html#post11084997


If the flow meter output was just a tube going to the bottom of the tank that would be correct. However, because we're going through a air diffuser the pressure can build up quite a bit more, especially if one is using a inline diffuser. 

As an example, my meter shows a flow of 16cc/min with an output pressure of 26 psi. Doing the math, my actual flow is 58 cc/min. If the output pressure was 1/2, say 13 psi, then the actual flow would be 47 cc/min.


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## OVT (Nov 29, 2011)

I would venture that pressures at the input and the output of a flow meter are the same and are ~ equal to the working pressure.


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## burr740 (Feb 19, 2014)

OVT said:


> I would venture that pressures at the input and the output of a flow meter are the same and are ~ equal to the working pressure.


 I believe this is right. But from what Ken is saying, if Im understanding correctly, the resistance at the end of the line (diffuser, reactor, etc) influences the actual cc/mn compared to what the flow meter says.

I stopped using flow meters on all my tanks. Between the one that leaked, and another with a stuck indicator ball that I still had to rely on a bubble counter to adjust, they became more trouble than they were worth.

Didnt trust them after this happened -


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## AguaScape (Oct 28, 2018)

OVT said:


> I would venture that pressures at the input and the output of a flow meter are the same and are ~ equal to the working pressure.


I believe that the defining line is the pressure before and after the needle valve/flow meter combo. I agree with OVT on the ~ equal part as long as there is significant resistance to flow downstream (like a diffuser). With a reactor the resistance is pretty much free flow with back pressure only provided by head height, so there could be a significant difference in pressure before and after the needle valve/flow meter. This could significantly affect the indicated vs actual flow on a flow meter.


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## Ken Keating1 (Nov 22, 2017)

OVT said:


> I would venture that pressures at the input and the output of a flow meter are the same and are ~ equal to the working pressure.


It depends on how the valve is being used in the flow meter. If it's being used to throttle back the air, then they'll be a pressure drop across it. In my system, I'm using the needle valve at the CO2 tank to control the flow and the valve in the flow meter is wide open. In this case pressure drop across the flow meter would be less. 

The pressure setting for my CO2 regulator is set at 40 PSI. The flow meter is about 8' away, and it's output pressure is 26 psi, so I have a 14 psi drop between the regulator and flow meter output. Most likely, the majority of the pressure drop is occurring across the needle valve at the output of the regulator.


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## Ken Keating1 (Nov 22, 2017)

AguaScape said:


> I believe that the defining line is the pressure before and after the needle valve/flow meter combo. I agree with OVT on the ~ equal part as long as there is significant resistance to flow downstream (like a diffuser). With a reactor the resistance is pretty much free flow with back pressure only provided by head height, so there could be a significant difference in pressure before and after the needle valve/flow meter. This could significantly affect the indicated vs actual flow on a flow meter.


The difference in pressure across the flow meter does come into play in the actual flow based on the calculations. It's only based on the flow meter output pressure which makes sense because the output pressure determines the density of the CO2 as it's exiting the flow meter. As an example, if the pressure drop across the flow meter is 100 psi, and the pressure output is 50 psi, the flow would still be the same if the pressure drop was 5 psi as long as the output is still 50 psi.


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## AguaScape (Oct 28, 2018)

OVT said:


> I would venture that pressures at the input and the output of a flow meter are the same and are ~ equal to the working pressure.





Ken Keating1 said:


> The difference in pressure across the flow meter does come into play in the actual flow based on the calculations. It's only based on the flow meter output pressure which makes sense because the output pressure determines the density of the CO2 as it's exiting the flow meter. As an example, if the pressure drop across the flow meter is 100 psi, and the pressure output is 50 psi, the flow would still be the same if the pressure drop was 5 psi as long as the output is still 50 psi.


I see what you mean. The actual flow is a combination of both pressure and volume. Higher back pressure will show a lower indicated flow than there really is due to the compression of the gas. A flow meter can only measure the actual flow and not adjust for the expansion of the gas after it is released from that back pressure.


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## Ken Keating1 (Nov 22, 2017)

AguaScape said:


> I see what you mean. The actual flow is a combination of both pressure and volume. Higher back pressure will show a lower indicated flow than there really is due to the compression of the gas. A flow meter can only measure the actual flow and not adjust for the expansion of the gas after it is released from that back pressure.


It's really the opposite, the higher the output pressure, the greater the actual flow will be above the flow meter reading. But remember, the actual flow is a calculated flow at atmospheric pressure(0 PSI). So if you have two gases flowing through meters at the same speed, and one gas is at 10 psi and the other is at 20 psi, and you captured the gases afterwards and released them into the air, the 20 psi gas would take up twice the volume than the 10psi gas because it was twice as dense.

Bump:


burr740 said:


> I stopped using flow meters on all my tanks. Between the one that leaked, and another with a stuck indicator ball that I still had to rely on a bubble counter to adjust, they became more trouble than they were worth.


On your 120 gallon tank, I would think the bubble count could be so fast it would be difficult to count. Is that the case?


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## AguaScape (Oct 28, 2018)

Ken Keating1 said:


> It's really the opposite, the higher the output pressure, the greater the actual flow will be above the flow meter reading. But remember, the actual flow is a calculated flow at atmospheric pressure(0 PSI). So if you have two gases flowing through meters at the same speed, and one gas is at 10 psi and the other is at 20 psi, and you captured the gases afterwards and released them into the air, the 20 psi gas would take up twice the volume than the 10psi gas because it was twice as dense.


Maybe it came across differently than I meant?


> Higher back pressure will show a lower indicated flow than there really is due to the compression of the gas.


 I was saying that the actual flow under pressure will be more than indicated on the meter.


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## AguaScape (Oct 28, 2018)

This does bring up an interesting point though. A system with higher back pressure (like a diffuser) would require a more precise flow gauge than the same tank using a reactor.


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## burr740 (Feb 19, 2014)

Ken Keating1 said:


> On your 120 gallon tank, I would think the bubble count could be so fast it would be difficult to count. Is that the case?


Definitely, and its the same on the 75s. I use those big inline Fluval bubble counters. Have a pretty good idea what the stream is supposed to look like. So I just eyeball it and fine tune by checking the PH. After that I can pretty much glance and see if its running properly. But yeah you can forget about actually counting bubbles

In the vid Gregg posted of his flow meter one time, the ball moved slow and steady when he turned the knob up or down. Mine never worked like that, none of the three. The slightest touch would send it flying, then a few minutes later it would finally settle on something. They all did that. Idk why

The good news was once I finally got them set they would stay there. That is as long as they didnt spring a leak like the one I showed in the video. After that I was like, nah...


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## AguaScape (Oct 28, 2018)

burr740 said:


> Definitely, and its the same on the 75s. I use those big inline Fluval bubble counters. Have a pretty good idea what the stream is supposed to look like. So I just eyeball it and fine tune by checking the PH. After that I can pretty much glance and see if its running properly.
> 
> In the vid Gregg posted of his flow meter one time, the ball moved slow and steady when he turned the knob up or down. Mine never worked like that, none of the three. The slightest touch would send it flying, then a few minutes later it would finally settle on something. They all did that. Idk maybe I did something wrong connecting them or whatever.
> 
> The good news was once I finally got them set they would stay there. That is as long as they didnt spring a leak like the one I showed in the video. After that I was like, nah...


Maybe you got a little moisture in them? Even a tiny bit of moisture will play havoc with a flow meter. I use multiple check valves to make sure that there is no chance water can get into them. They work buttery smooth for me.


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## burr740 (Feb 19, 2014)

One got thoroughly soaked. The other two didnt as far as I know. But they were all like that from the very beginning.


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## Grobbins48 (Oct 16, 2017)

burr740 said:


> One got thoroughly soaked. The other two didnt as far as I know. But they were all like that from the very beginning.


Now I need to check something. One of my flow meters bounces a bit before it settles, while another one was always rock solid. I'll have to look into them today since I only use one now. Might swap it for the other and see. 


And Ken, good find. I have read those directions but completly glanced over the formulas. Just goes to show what you can learn from reading what the manufacturer prints!
Good this is that the readings are all relative, so as long as you k ow your settings you are good. Bad news is this makes it more difficult to compare readings. Good to know!

And another thought, if I am looking at and completing the equation properly the pressure will have a much greater influance than the temperature. I would guess most of us are around 68-74 ambient air, it even up in the 80's that is less than 1cc/min change at 0PSI. 

Now I'm curious my output pressure on the flow meter... just because!


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## Greggz (May 19, 2008)

burr740 said:


> In the vid Gregg posted of his flow meter one time, the ball moved slow and steady when he turned the knob up or down. Mine never worked like that, none of the three. The slightest touch would send it flying, then a few minutes later it would finally settle on something. They all did that. Idk why


Interesting Joe, I really don't know what would make that happen? Someone here suggested maybe a leak somewhere? Wish I knew what was going on with yours and could help.

I can only speak to my own experience of running mine for three years. Rock solid and I wouldn't be without it. 

FWIW, running mine at about 45 cc/min at 20 PSI into a 20' Cerges for my 120G.

And I don't think we will ever know the actual flow rate. But that was never the point. 

Back when I started down this path, my goal was to more accurately adjust the relative flow rate. To me, true absolute value doesn't really matter. 

If anyone wants to see how this whole thing got started, here is the thread I started in 2015 searching for a better solution. It was my first post on this forum. I had just added CO2 to the tank and was as newbie as they come. Funny thing is I found mention of the Dwyer on this site from a post in 2012. 

And for those who have been around for awhile, it was my first interaction with Sol. I just read it again for the first time in a long time, and his comments still have me scratching my head?? This was during the days of the microtox wars. 

https://www.plantedtank.net/forums/9-equipment/959321-must-something-better-than-bubble-counter.html#post8571641


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## Cichlid-140 (Sep 28, 2018)

Ken Keating1 said:


> I've snipped the formula's from the pdf link I provided above:





Ken Keating1 said:


> It depends on how the valve is being used in the flow meter. If it's being used to throttle back the air, then they'll be a pressure drop across it. In my system, I'm using the needle valve at the CO2 tank to control the flow and the valve in the flow meter is wide open. In this case pressure drop across the flow meter would be less.
> 
> The pressure setting for my CO2 regulator is set at 40 PSI. The flow meter is about 8' away, and it's output pressure is 26 psi, so I have a 14 psi drop between the regulator and flow meter output. Most likely, the majority of the pressure drop is occurring across the needle valve at the output of the regulator.


You forgot to throw in the adjustment for Specific Gravity. It's different between different gasses or gas mixtures. Too many variable to get an accurate number, but you can be confident of the repeatability and relative reading if the flowmeter is clean and in good repair.


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## Ken Keating1 (Nov 22, 2017)

Cichlid-140 said:


> You forgot to throw in the adjustment for Specific Gravity. It's different between different gasses or gas mixtures. Too many variable to get an accurate number, but you can be confident of the repeatability and relative reading if the flowmeter is clean and in good repair.





Greggz said:


> And I don't think we will ever know the actual flow rate. But that was never the point.


 I agree! The RMA series flowmeters have an accuracy of 4%. Combine that with the accuracy of the pressures gauges and temperature gauges and we're really dealing with numbers that are not going to be spot on. I always felt if we wanted accurate numbers we'd have to use mass flow meters or go by daily weight by weighing our tanks. But for our purposes a relative number is all we need because the critical point is how are plants react in our individual tanks. Folks could all have the same size tanks, but depending on the plants, plant density, lighting, sump size, water surface area, etc, there could be a large variance in CO2 requirements.


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## Letsfish (Jul 11, 2017)

I have a post body kit with a Fabco needle valve which controls the CO2 flow doesn`t that make the SS valve on the flow meter be unnecessary?


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## Ken Keating1 (Nov 22, 2017)

Letsfish said:


> I have a post body kit with a Fabco needle valve which controls the CO2 flow doesn`t that make the SS valve on the flow meter be unnecessary?


The flowmeter valve is not necessary, it's more of an convenient accessory. Some folks have the CO2 tank remote, say in a basement or closet and the flow meter in the cabinet under the aquarium, so it's nice to be able to control it at the flow meter where you can see the diffuser bubbles as your adjusting the flow rate.


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## Letsfish (Jul 11, 2017)

Mine would go between the needle valve and a inline atomizer on the outflow hose on the canister. Right now I have a Fuval inline bubble counter there.


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## Greggz (May 19, 2008)

Letsfish said:


> I have a post body kit with a Fabco needle valve which controls the CO2 flow doesn`t that make the SS valve on the flow meter be unnecessary?


Maybe.

I have experience controlling flow with both the needle valve and the flow meter valve.

To me, I much prefer using the flow meter valve. Easier to dial in and remains more stable. 

Again, just my personal preference after three years of use. And it's only about $12.00 more, so skipping the valve is not saving much.


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## Mike A. (Jan 6, 2018)

Grobbins48 said:


> Now I need to check something. One of my flow meters bounces a bit before it settles, while another one was always rock solid. I'll have to look into them today since I only use one now. Might swap it for the other and see.


Set one up the other day and it was doing the same. It was a small, slower leak that I'd missed on earlier quick testing. I believe what's happening with the bounce is that pressure is building then releasing through the leak, ball tries to stabilize, builds then releases, ball bounces again... With such a small scale on these things just tiny amount of variance will show. Mine was just a very small seep that I didn't see until pressure on the low side was higher and after I wet everything down good and let it sit long enough to catch it.


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## Cichlid-140 (Sep 28, 2018)

Mike A. said:


> Set one up the other day and it was doing the same. It was a small, slower leak that I'd missed on earlier quick testing. I believe what's happening with the bounce is that pressure is building then releasing through the leak, ball tries to stabilize, builds then releases, ball bounces again... With such a small scale on these things just tiny amount of variance will show. Mine was just a very small seep that I didn't see until pressure on the low side was higher and after I wet everything down good and let it sit long enough to catch it.


Another possible plus for the flowmeters. I don't know if you'd catch the difference with a bubble counter.


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## Rush3737 (Jan 15, 2013)

I'm currently having some issues with my new 151. Whether I run the flowmeter open and adjust with the needle valve or if I open the needle valve a bit and try to limit with the flowmeter I run into the same issue. I can do adjustments below 20 fine, but if I try to edge it above that it quickly skyrockets to the top of the chart. I got it dialed in at 25-30 after much trying about an hour ago, but will see if it holds.


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## Ken Keating1 (Nov 22, 2017)

Rush3737 said:


> I'm currently having some issues with my new 151. Whether I run the flowmeter open and adjust with the needle valve or if I open the needle valve a bit and try to limit with the flowmeter I run into the same issue. I can do adjustments below 20 fine, but if I try to edge it above that it quickly skyrockets to the top of the chart. I got it dialed in at 25-30 after much trying about an hour ago, but will see if it holds.


You may want to try different regulator output pressures and see if that helps. I've seen the same with my system. I'm guessing the diffusers are not linear devices, so a little pressure increase may cause a lot more flow. When it jumps up in flow, does it settle down in say 10 to 15 minutes? I've also noticed if the CO2 has been off for a few hours, the diffuser takes about 30 minutes to become steady and I'm assuming that's because water has been soaking into the diffuser when no CO2 flow is occurring.


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## Rush3737 (Jan 15, 2013)

Ken Keating1 said:


> You may want to try different regulator output pressures and see if that helps. I've seen the same with my system. I'm guessing the diffusers are not linear devices, so a little pressure increase may cause a lot more flow. When it jumps up in flow, does it settle down in say 10 to 15 minutes? I've also noticed if the CO2 has been off for a few hours, the diffuser takes about 30 minutes to become steady and I'm assuming that's because water has been soaking into the diffuser when no CO2 flow is occurring.


Let me go over things a bit more as adjusting output pressure isn't an option. I'm still working through how the results settle over time, but so far I only have it dialed in to: Whatever I have it at now it probably won't be that tomorrow, which to me was quite the opposite of what I expected from this instrument. 

I have the following setup from amazon for a regulator, so output pressure is a constant at 75psi: https://smile.amazon.com/gp/product/B07HNQZ616/ref=oh_aui_search_asin_title?ie=UTF8&psc=1

From there I go to the flowmeter, which then goes to a brass check valve, plastic check valve, and finally onto my Rex Griggs reactor.


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## Greggz (May 19, 2008)

Rush3737 said:


> I have the following setup from amazon for a regulator, so output pressure is a constant at 75psi: https://smile.amazon.com/gp/product/B07HNQZ616/ref=oh_aui_search_asin_title?ie=UTF8&psc=1


Wow 75psi fixed!

I honestly have no idea how that would affect the operation of the meter.

I'll have to test mine at various pressures to see if there is an effect. I can tell you this, mine runs super smoothly, but I guess we all have different conditions.

Here is the way it should work. I made this video a while back to show Burr.


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## Mike A. (Jan 6, 2018)

Rush3737 said:


> I have the following setup from amazon for a regulator, so *output pressure is a constant at 75psi*: https://smile.amazon.com/gp/product/B07HNQZ616/ref=oh_aui_search_asin_title?ie=UTF8&psc=1


^ As they say, there's your problem right there.

With mine once you start approaching +50-ish psi it starts heading for the top quickly. Max pressure for these is only 100 psi. Typically for such things you want to be more at about half of that as a good working range. I've not tried to crank mine that high but wouldn't be surprised that it's getting off scale especially into a reactor with little back pressure to throttle the flow any. You're kinda just blasting gas through it.


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## Grobbins48 (Oct 16, 2017)

Yeah 75 does seem pretty high. I have been running 40, but mainly due to the fact that I used to run two tanks off one regulator, and one was a diffuser which really did need the pressure to work properly. 

I'll mess around with the pressure tomorrow too to see how things work on my end. Who knows, I might even lower it a bit now.


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## Cichlid-140 (Sep 28, 2018)

Rush3737 said:


> Let me go over things a bit more as adjusting output pressure isn't an option. I'm still working through how the results settle over time, but so far I only have it dialed in to: Whatever I have it at now it probably won't be that tomorrow, which to me was quite the opposite of what I expected from this instrument.
> 
> I have the following setup from amazon for a regulator, so output pressure is a constant at 75psi: https://smile.amazon.com/gp/product/B07HNQZ616/ref=oh_aui_search_asin_title?ie=UTF8&psc=1
> 
> From there I go to the flowmeter, which then goes to a brass check valve, plastic check valve, and finally onto my Rex Griggs reactor.


The GLA reg's safety pressure relief trips at between 52 and 54psi. Good luck with that one.


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## Jcricket (Nov 30, 2018)

AguaScape said:


> This does bring up an interesting point though. A system with higher back pressure (like a diffuser) would require a more precise flow gauge than the same tank using a reactor.


This makes a lot of sense with a problem I am having. A setting of 20cc/min with a psi of 10 is a very different MASS of gas at 20cc/min and 40psi. If it is linear it would be 4 times the co2 at the same flow rate. I hope this makes sense. It explains a problem I am having. Or does it?

Edit: I just did a quick experiment. I tuned on my co2 system and read what the flow rate was. It is set to 2cc/min at 35psi. I then disconnected the diffuser. It jumped to 22cc/min at 35psi.


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## AguaScape (Oct 28, 2018)

Jcricket said:


> This makes a lot of sense with a problem I am having. A setting of 20cc/min with a psi of 10 is a very different MASS of gas at 20cc/min and 40psi. If it is linear it would be 4 times the co2 at the same flow rate. I hope this makes sense. It explains a problem I am having. Or does it?
> 
> Edit: I just did a quick experiment. I tuned on my co2 system and read what the flow rate was. It is set to 2cc/min at 35psi. I then disconnected the diffuser. It jumped to 22cc/min at 35psi.


I don't think that measured flow with no back pressure equates to actual flow with back pressure. The back pressure is an essential part of the equation. I doubt that it scales linearly. Very few things do. I may need to delve into the formula further as I do run flow meters and this interests me.


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## jeffkrol (Jun 5, 2013)

AguaScape said:


> I don't think that measured flow with no back pressure equates to actual flow with back pressure. The back pressure is an essential part of the equation. I doubt that it scales linearly. Very few things do. I may need to delve into the formula further as I do run flow meters and this interests me.





https://www.sensorsmag.com/components/basics-rotameters
where: 

*Q* = volumetric flow rate, e.g., gallons per minute *k* = a constant *A* = annular area between the float and the tube wall *g* = force of gravity *h* = pressure drop (head) across the float







(1)

For the really anal keep in mind that the scale and floaty ball are calibrated to a specific gas..
See table 1:
https://www.mathesongas.com/pdfs/products/flowmeter-product-line-overview.pdf


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## Jcricket (Nov 30, 2018)

Jcricket said:


> This makes a lot of sense with a problem I am having. A setting of 20cc/min with a psi of 10 is a very different MASS of gas at 20cc/min and 40psi. If it is linear it would be 4 times the co2 at the same flow rate. I hope this makes sense. It explains a problem I am having. Or does it?
> 
> Edit: I just did a quick experiment. I tuned on my co2 system and read what the flow rate was. It is set to 2cc/min at 35psi. I then disconnected the diffuser. It jumped to 22cc/min at 35psi.


Hey Jeff,
Thanks for all of the input. I can follow formulas, but the root understanding is mostly above my head. When I think back to chemisty(a zillion years ago), we talked about mols. This was the actual amount(in molecules IIRC) of the compound or element being considered. Because the co2 is a gas, and gas compresses, then the pressure becomes a critical component in the delivery of the CO2. 

I have a question that is very simplified that is probably quite incorrect but presented in this manner to help demonstrate and understand what is going on here. The example.
My flow meter is registering 10cc/min at 5psi and I am delivering 1 mol of co2, no obstruction after it. Part two I add a diffuser or obstruction after.
My flow meter is still registering 10cc/min but at 20psi. I have four times the pressure so the gas has to compress. I am certain I am delivering more co2 in the same volume of space. Would it be 4x time the number of mols of co2? 
And then the big question. Since the density of the gas is clearly affected by the PSI, then the flow meter becomes "un-calibrated" as to the actual amount of co2 being delivered. How does a person compensate for this, or is it possible? Way above the scope of this hobby? 

I am thinking it is best to use the system(regulators, and gauges) as a way to stabilize the delivery of the co2 into the aquarium. Use the ph/kh tables as the measurment for dissolved co2 and do not rely on the gauge and meters.


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## Ken Keating1 (Nov 22, 2017)

@Jcricket: Is the pressure your stating at the output of the flow meter or at the regulator? If it's the flowmeter output then I can calc the volume of CO2 at atmospheric pressure for the various pressures/flowrates. If the pressure is not at the flowmeter output then it's can't be calculated. The correction formula needs the output pressure to determine the actual flow rate.


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## Ken Keating1 (Nov 22, 2017)

AguaScape said:


> I don't think that measured flow with no back pressure equates to actual flow with back pressure. The back pressure is an essential part of the equation. I doubt that it scales linearly. Very few things do. I may need to delve into the formula further as I do run flow meters and this interests me.


It can be calculated because there's still atmospheric pressure on the output at 14.7 pounds. If you plug the numbers into the equation in post 23, assuming the gas was at 70 degrees F for which the flow meters are calculated for, then the value under the square root sign becomes 1, as such the meter reading is the actual flow. Remember, the meter readings are only correct if the output pressure is 0 psi( or 14.7 psi atmospheric pressure). With any other output pressures we have to calculate to obtain the actual flow rate.


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## Ken Keating1 (Nov 22, 2017)

jeffkrol said:


> https://www.sensorsmag.com/components/basics-rotameters
> 
> https://www.mathesongas.com/pdfs/products/flowmeter-product-line-overview.pdf


Great reference info on rotometers, thanks for posting this.


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## OVT (Nov 29, 2011)

Flow meter - an alternative to bubble counters for larger tanks.

Beyond that it is still too many steps away from measuring what we think is important, i.e. co2 concentration in water at any given time.
And even then, I am still not convinced that the magic 30 ppm is the "best" in all cases and is the target to hit to grow all plants to their "best potential".

My thinking is that defining "the best" is impossible as there is always be n + 1.

If our goal is to be able to reproduce someone else's result by replicating their environment, then our next technical quest should be measuring de-gasing. Or abolishing Mondays.


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## Grobbins48 (Oct 16, 2017)

OVT said:


> Or abolishing Mondays.


Agree with the whole post, but this gets the prize!


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## Greggz (May 19, 2008)

OK this has gone down an interesting road.

So let's look at this from another angle, taking the numbers from my tank. 

If CO2 is on for 8.5 hours = 510 minutes per day.

510 minutes x 75 days = 38,250 minutes.

Meter set at 50 cc/min = 1,912,500 cc.

A 10lb CO2 tank = 87 cubic feet.

87 cubic feet = 2,465,357 cc

But calculating the absolute value of cc/min was never the point.

The focus for me has always been on better controlling relative values. 

Numbers above would indicate my actual flow rate to be 64.45 cc/min. Meaningless to me, but interesting nonetheless.


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## Grobbins48 (Oct 16, 2017)

Greggz said:


> OK this has gone down an interesting road.
> 
> 
> 
> ...


This is a good point. I remember many months ago I was wondering why the tank went empty 'early' after doing these calculations. Figured I has 30ish more days left. After this thread it is likely that my actual cc/min was much higher than I thought, and thus my math was right, just using the wrong cc/min.

It all slowly comes together...


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## Edward (Apr 11, 2005)

I keep a record of the last 45 CO2 tank refills. It is never the right amount as it varies from 15.2 lb. to 20.8 lb., interestingly enough but not surprising is that the expected quantity of 20 lb. it reached only 4x out of the 45 refills. All of the 41 refills were much less than 20 lb. So matching CO2 tank size with the flow meter settings can be pretty misleading. 


OVT said:


> And even then, I am still not convinced that the magic 30 ppm is the "best" in all cases and is the target to hit to grow all plants to their "best potential".


 I remember reading on this forum about too high CO2 concentrations be potentially harmful to aquatic plants. Anybody seen any evidence on that? I haven’t.


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## Greggz (May 19, 2008)

Edward said:


> I keep a record of the last 45 CO2 tank refills. It is never the right amount as it varies from 15.2 lb. to 20.8 lb., interestingly enough but not surprising is that the expected quantity of 20 lb. it reached only 4x out of the 45 refills. All of the 41 refills were much less than 20 lb. So matching CO2 tank size with the flow meter settings can be pretty misleading.


Edward that is a good point.

And I should have qualified my calculations, as like you said, who knows what your actual cubic feet of CO2 from a fill, or lots of other variables.

When I did the math, I was actually pleasantly surprised that is was somewhere in the ball park.


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## Ken Keating1 (Nov 22, 2017)

Here's my numbers, but mine are based on the flow rate I calculated in Post #26. 

CO2 Run time: 6 hrs/day x 60 min/Hr = 360 min

Calculated Flow Rate per Post #26 = 58 cc/min

Total cc/Day = 58 x 360 = 20,880 cc

cc/10 lb tank = 2,465,357 cc

Calculated # of days in tank = 2,465,357 cc / 20,880 cc per day = 118 days.

Date started using full tank: 7/8/18

Date tank was empty: 11/8/18

# of Days: 124

Error %: 5 %.

Wow, that's a lot closer than I would of thought. 

Now, for those that are probably borderline OCD, we weigh the tanks when full and at empty to know exactly how much is used. Unfortunately I have those weights. But that's a another set of calcs I'm not sure I want to research at this time!


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## Rush3737 (Jan 15, 2013)

This damn place...

I should have known better to think I could cut back anywhere. Got that Reg/Sol/NV/BC setup because it seemed to be an inexpensive way to get back into things. But then everyone made the flowmeter out to be such a great tool I broke down and bought that, and now they may not play well together. 

Whatever, I just did what I should have done from the start and got the following:

372573244694 (reg)
121090156302 (sol)

Once both arrive I'm going to first try running Reg>Sol>FM to see if the needle valve can reliably be cut out on my system. If not I'll steal the NV from my current setup and throw it in there.


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## Greggz (May 19, 2008)

Rush3737 said:


> This damn place...


LOL!:grin2:


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## Jcricket (Nov 30, 2018)

Ken Keating1 said:


> @Jcricket: Is the pressure your stating at the output of the flow meter or at the regulator? If it's the flowmeter output then I can calc the volume of CO2 at atmospheric pressure for the various pressures/flowrates. If the pressure is not at the flowmeter output then it's can't be calculated. The correction formula needs the output pressure to determine the actual flow rate.


The psi as at the outlet(low pressure side) on the regulator. After the regulator is the solenoid valve, then the flow meter, then the aquarium - currently using a diffuser but very soon will be a griggs reactor.

So adding a gauge after the flow meter might be a benefit? Easy enough if it will help.

Bump:


Greggz said:


> OK this has gone down an interesting road.
> 
> So let's look at this from another angle, taking the numbers from my tank.
> 
> ...


A valid point for sure. However, being the newbie I am, I am looking for a foundation from which to stand safely on. My last attempt at a planted tank, years ago, resulted in a few co2 overdoses and fish crashes. Because I am so much more involved this time with much better lighting and much better fertilizers, I am trying to "dial in" the tank. This means I am going to be adjusting the various thing like light, ferts, and co2. I just want to have at least an idea of what I am doing without "learning" through catastrophe. 

The 2cc/min I posted earlier seems to work pretty well. I am holding 6.6-6.8ph. I suspect I have a fairly plugged up diffuser so when the co2 finally gets through, it is a bit compressed.


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## Ken Keating1 (Nov 22, 2017)

Jcricket said:


> The psi as at the outlet(low pressure side) on the regulator. After the regulator is the solenoid valve, then the flow meter, then the aquarium - currently using a diffuser but very soon will be a griggs reactor.
> So adding a gauge after the flow meter might be a benefit? Easy enough if it will help.


To obtain the true flow, you need the flow meter output pressure, and then you have to calculate to obtain the actual flow. *But please note, no one here on TPT does this*, at least not that I'm aware of, but I'm pretty sure no one does. The flow meter is just used as a reference point, that is, you use it to compare day to day numbers. If it's set at 10, and you want to bump it up, you adjust to 11. If it's set at 10 today, it should be at 10 tomorrow. So for now, don't worry about true flow, adjust your flow by how the plants and fish respond, that's really the important part.


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## Jcricket (Nov 30, 2018)

Ken Keating1 said:


> To obtain the true flow, you need the flow meter output pressure, and then you have to calculate to obtain the actual flow. *But please note, no one here on TPT does this*, at least not that I'm aware of, but I'm pretty sure no one does. The flow meter is just used as a reference point, that is, you use it to compare day to day numbers. If it's set at 10, and you want to bump it up, you adjust to 11. If it's set at 10 today, it should be at 10 tomorrow. So for now, don't worry about true flow, adjust your flow by how the plants and fish respond, that's really the important part.


Okay. So overkill, overthink and over complicate. My wife says this should be my mantra............:nerd:


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## KZB (Jan 3, 2018)

Ken Keating1 said:


> So for now, don't worry about true flow, adjust your flow by how the plants and fish respond, that's really the important part.


Mr.Ken is absolutely right. I believe one of the ideal purposes of a flow meter is to bring you back to your co2 range time after time after tank refills. Try to simplify and enjoy the ride


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## Cichlid-140 (Sep 28, 2018)

Jcricket said:


> Okay. So overkill, overthink and over complicate. My wife says this should be my mantra............:nerd:


Yeah - I guess you could spend an entire evening taking the spectral analysis of a sunset but I think you'd be missing the point.


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## Grobbins48 (Oct 16, 2017)

For me I know my flow meter is providing the utility that I want it to, which is an enhanced version of a bubble counter.

I do enjoy these conversations talking about the different variables and their impacts- just another fun part of this hobby for me. Ultimately though, I am happy with the performance!


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## KayakJimW (Aug 12, 2016)

Jcricket said:


> Okay. So overkill, overthink and over complicate. My wife says this should be my mantra............:nerd:


"You're asking how a watch works... For now, just keep an eye on the time"

-Benicio Del Toro in Sicario

This is one of my favorite movie lines ever. I have to tell it to myself just about every day!


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## Ken Keating1 (Nov 22, 2017)

Jcricket said:


> Okay. So overkill, overthink and over complicate. My wife says this should be my mantra............:nerd:


Funny, this sort of reflects this thread. The OP was "Does anyone know what ports on the Dwyer are for input and output?" and look what path it went on!


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## Grobbins48 (Oct 16, 2017)

Ken Keating1 said:


> Funny, this sort of reflects this thread. The OP was "Does anyone know what ports on the Dwyer are for input and output?" and look what path it went on!


Good point... This one did sort of get away from us!


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## Cichlid-140 (Sep 28, 2018)

Ken Keating1 said:


> Funny, this sort of reflects this thread. The OP was "Does anyone know what ports on the Dwyer are for input and output?" and look what path it went on!


Topics acquire a life of their own.


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## KayakJimW (Aug 12, 2016)

Haha, yep! And one that has helped me (for one) quite a bit... Changed my gameplan to pick up the 150 ssv instead of the 151, and now feel like I'll actually know how to approach the setup, hardware, tuning, troubleshooting, etc once it arrives. Thanks all!


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## PlantedRich (Jul 21, 2010)

For sizing and choosing which flowmeter will best suit, I feel it is very important to do some testing first. I don't find pressure will have much to do with the choice as what goes in the meter, comes out of the meter, and what hits the tank are going to be the same amount unless you have a leak. 
But that is about as far as I go on things being the same from tank to tank. We all know counting bubbles is not the same and I find the same with flowmeters as different tanks require totally different CO2 amounts. But there is one sure way to get very close to what amount you do need the meter to measure. 
We can certainly go with the idea that the meter which reads a broad range will fit more tanks but that comes at the price of loss of precision in the metering. If your car speedometer reads 0-140 with marks every ten MPH, we do not get the same precision as we get with a meter that reads each MPH! Same with any meter, so getting the one which best reads the range you want, will automatically give you better precision. 
So if you have the tank set and working, so some testing first. Stick the end of a CO2 tube up into an overturned vial, etc. and measure how much CO2 you are adding and then go to one of the online conversion calcs to figure how much that is in the type of flowmeter you are looking at buying. You may measure in CC per minute and want to use a meter speaking cubic inches per hour, so some calculations/conversions may be needed? 
For my use, I do not find the valves on any of the flowmeters to be precise enough for what I want and I do use needle valves, even when the meter has one on it.


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## Grobbins48 (Oct 16, 2017)

@PlantedRich funny that you just posted here, as someone just today created a thread wondering where you were!


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## Letsfish (Jul 11, 2017)

I am in the process of re-doing my Co2 system.I am going to eliminate my inline atomizer and bubble counter and replace them with Griggs reactor and a Dwyer flow meter There are 2 reasons for this move, the is atomizer leaking and it is a estimated guess on how many bubbles is actually coming out of it bubble counter.So I guess I will have to rely on the drop checker and PH readings until I get everything dialed in. I am kind of lucky that all of my plants are low tech so maybe in the future I might venture into some more demanding plants but for right now I am satisfied.I do like the idea of the atomizer concept it is compact and does a good job but they are made to break and at $40 buck a pop I am done with em.


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## houstonreef (Aug 24, 2018)

Letsfish said:


> I am in the process of re-doing my Co2 system.I am going to eliminate my inline atomizer and bubble counter and replace them with Griggs reactor and a Dwyer flow meter There are 2 reasons for this move, the is atomizer leaking and it is a estimated guess on how many bubbles is actually coming out of it bubble counter.So I guess I will have to rely on the drop checker and PH readings until I get everything dialed in. I am kind of lucky that all of my plants are low tech so maybe in the future I might venture into some more demanding plants but for right now I am satisfied.I do like the idea of the atomizer concept it is compact and does a good job but they are made to break and at $40 buck a pop I am done with em.


Go with Reactor and you never regret. i used to have 2 atomized in-line diffusors for my tank. i had to dip them in bleach every 2 weeks. I built a Griggs reactor and loving it. it cut down greatly in maintenance time. If you want to build yours with clear tube, i can tell you where to buy the clear tube. it is very cheap.


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## Bettatail (Feb 12, 2009)

Damn it, I missed the party..


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## KayakJimW (Aug 12, 2016)

Bettatail said:


> Damn it, I missed the party..


I'm still partyin' with my Dwyer. Grab a drink out the fridge and tell us your thoughts


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## Bettatail (Feb 12, 2009)

KayakJimW said:


> I'm still partyin' with my Dwyer. Grab a drink out the fridge and tell us your thoughts


I've been walking in the dark alone, until I saw this thread today.


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## Greggz (May 19, 2008)

KayakJimW said:


> I'm still partyin' with my Dwyer. Grab a drink out the fridge and tell us your thoughts


Me too!

IMO, for any tank 55G or over, it's a much better solution to dialing in CO2 flow rate.


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## Grobbins48 (Oct 16, 2017)

Greggz said:


> Me too!
> 
> IMO, for any tank 55G or over, it's a much better solution to dialing in CO2 flow rate.


Still love that I have mine! Been quite solid this whole time!


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## Quagulator (May 4, 2015)

I wonder how long it will take (if ever at all) aquarium CO2 kit manufactures will start including their own flow meters instead of bubble counters aimed at large tanks... 

I doubt it will ever happen, and if it did they would be poor quality flow meters....


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## Grobbins48 (Oct 16, 2017)

Quagulator said:


> I wonder how long it will take (if ever at all) aquarium CO2 kit manufactures will start including their own flow meters instead of bubble counters aimed at large tanks...
> 
> I doubt it will ever happen, and if it did they would be poor quality flow meters....


Quality is exactly what my concern would be. There is endless discussion on the quality and holding power of different needle valves on this forum. From those who run the Dwyer I have seen very little as far as complaints if it is installed correctly. Maybe a little touchy to dial in initially, but once it is set seems to be rock solid.


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## houstonreef (Aug 24, 2018)

burr740 said:


> Definitely, and its the same on the 75s. I use those big inline Fluval bubble counters. Have a pretty good idea what the stream is supposed to look like. So I just eyeball it and fine tune by checking the PH. After that I can pretty much glance and see if its running properly. But yeah you can forget about actually counting bubbles
> 
> In the vid Gregg posted of his flow meter one time, the ball moved slow and steady when he turned the knob up or down. Mine never worked like that, none of the three. The slightest touch would send it flying, then a few minutes later it would finally settle on something. They all did that. Idk why
> 
> The good news was once I finally got them set they would stay there. That is as long as they didnt spring a leak like the one I showed in the video. After that I was like, nah...


i am having the same problem listed above. it is very inconsistent and hard to adjust to the right level.


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## Grobbins48 (Oct 16, 2017)

houstonreef said:


> i am having the same problem listed above. it is very inconsistent and hard to adjust to the right level.


Did you ever over tighten it when mounting? This can cause the bouncing issue. Had it happen to one of mine when over tightening the mounting plates on the back....


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## jeffkrol (Jun 5, 2013)

Letsfish said:


> Mine would go between the needle valve and a inline atomizer on the outflow hose on the canister. Right now I have a Fuval inline bubble counter there.


The metering valve on the flowmeter is the EXACT same function as your Fabco..
Which one would decide to use is your call and based on which you may consider more precise..orr placement ect..

Dwyers pretty much have Fabco equiv or so I've been told..so using one or the other is a wash.

Some flowmeters have better metering valves than err "yours" (general statement).. so it would make the Fabco unnecessary..
Of course the exact flowmeter/valve and metering valve need to be known..
Meduium, high low.. 1-6 all different qualities of metering valves on a flowmeter.. Some good for us, some not..
The "1" is a low flow high precision valve equiv to a $99 Dakota metering valve.


> *(tech specs..VM1-BB-1A StraightBrass.....200 ml/min (g) max flow.... 0.042 Orifice .... 0.0005CV)*












Bump:


houstonreef said:


> i am having the same problem listed above. it is very inconsistent and hard to adjust to the right level.


They are extremely sensitive to dirt inside the tube...If it's not a leak it's dirt.. even a TEENY bit of it..
Would also suggest making sure it is dead plumb straight up and down..though I haven't found that a terrible problem if a SMALL tilt

Earlier in this thread someone mentioned getting mineral oil inside.. BAD .. 

Oh and some floats are more prone to sticking due to smaller mass..
Doesn't help w/ the small flows some use either..


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## jeffkrol (Jun 5, 2013)

Ken Keating1 said:


> he actual flow is a calculated flow at atmospheric pressure(0 PSI).


Stupid minor point of clarity.. Meters are calibrated at STP.. so not really at 0 psi.and at 70F





> Flow capacities shown in Tables 4, 5, 6 and 7 are based on calibrations at standard (STP) conditions (70 °F /21.1 °C and 14.7psia/1 atm abs). For fl uids other than air or water at STP conditions see paragraph on METER SIZING on page 59



http://www.aalborg.com/images/file_to_download/en_Aalborg_EM20200113_Technical_Information.pdf


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## Bettatail (Feb 12, 2009)

Quagulator said:


> I wonder how long it will take (if ever at all) aquarium CO2 kit manufactures will start including their own flow meters instead of bubble counters aimed at large tanks...
> 
> I doubt it will ever happen, and if it did they would be poor quality flow meters....


before I saw this thread today, I was more like in the parallel universe rather than walking along in the dark.
below are the flow meters that are good to use as dwyer RMA 150 or RMA 151, some of them can monitor flow rate much lower than dywer RMA.

check my metering valve selection thread in details, I've already listed them.


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## zmartin (May 1, 2018)

I have a RMA-151-SSV in the drawer (not in use). Which I must get back to Installing. 

What adaptors does everybody use to connect the CO2 line to the Dwyer? Does Dwyer sell these or are they third party?

Advice appreciated.


Sent from my iPhone using Tapatalk


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## Bettatail (Feb 12, 2009)

zmartin said:


> I have a RMA-151-SSV in the drawer (not in use). Which I must get back to Installing.
> 
> What adaptors does everybody use to connect the CO2 line to the Dwyer? Does Dwyer sell these or are they third party?
> 
> ...


Dwyer flowmeter default inlet/outlet is 1/8 female NPT.
a hose barb to 1/8 male npt adapter or a push and pull to 1/8 male npt adapter should work.


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## gentoo9ball (Aug 19, 2010)

*reviving an oldy Dwyer for ~240g*

What model should I look at for my 210 with a 40g sump? I use a herbie setup on my overflows to limit offgas. Off the return manifold I run a custom 4"x25" rex griggs reactor, so it's fairly efficient, but there's no way I could count bubbles in a bubble counter.

Which should I get:
RMA-150-SSV	Flowmeter, range 10-100 cc/min air. ±8% accuracy.	
RMA-151-SSV	Flowmeter, range 5-50 cc/min air. ±8% accuracy.	
RMA-11-SSV	Flowmeter, range 30-200 cc/min air.


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## Bettatail (Feb 12, 2009)

gentoo9ball said:


> What model should I look at for my 210 with a 40g sump? I use a herbie setup on my overflows to limit offgas. Off the return manifold I run a custom 4"x25" rex griggs reactor, so it's fairly efficient, but there's no way I could count bubbles in a bubble counter.
> 
> Which should I get:
> RMA-150-SSV	Flowmeter, range 10-100 cc/min air. ±8% accuracy.
> ...


They will work under certain condition, but I think you need to find the calibration data for co2 under different pressure settings, otherwise a flowmeter is only a bigger size bubble counter.
here is a newer thread for flowmeters, it will take some time to grab the ideas.

https://www.plantedtank.net/forums/9-equipment/1305023-flow-meters-our-pressurized-co2-system.html


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## jeffkrol (Jun 5, 2013)

> _Question
> I am looking to use an "Air" flowmeter RMA-6-SSV to monitor CO2 flow. I am wondering if there are are any concerns or correction factors I need to apply._
> Answer
> A specific gravity correction factor will need to be considered when monitoring other gases with a meter calibrated for air. The correction factor equation is as follows: Q2=Q1 x sqrt (1/S.G.) Where: Q1= Observed Flowmeter reading Q2= Standard Flow Corrected for Specific Gravity 1= Specific Gravity of Air or Water S.G.= Specific Gravity of media being used in flowmeter originally calibrated for air or water.
> ...


there is that...



> For further information, see our "Tech & Specs" Video Blog: Fix your Flow... Specific Gravity and Pressure Corrections for Variable Area Flowmeters (Episode 4), in Dwyer's Video Library


I have yet to find it.. 

PIA.............
http://blog.dwyer-inst.com/2017/04/13/ask-the-expert-using-flowmeters-with-different-medias/


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