# CO2 regulators - harbor freight anyone?



## Jcricket (Nov 30, 2018)

Hey,I bought an el-cheapo regulator off the bay. What a POS!!!!!!!
I am going to go over and look at two different models of co2 regulators from harbor freight. 
here they are:

https://www.harborfreight.com/regulator-gauge-94841.html


https://www.harborfreight.com/CO2Argon-Flow-Gauge-Regulator-63787.html

Has anyone else used one of these? I like the looks of the Olson. Thoughts on theses?


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## jeffkrol (Jun 5, 2013)

Well for one thing both are oddly marked in scfm or liters/minute not psi............

If you go like $70 might as well go all the way w/ a "real" regulator..

https://store.cyberweld.com/smco2re...MI6K77up3c3wIVyLrACh1OxwqxEAkYBSABEgJWIvD_BwE


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## Jcricket (Nov 30, 2018)

Hey Jeff,
Thanks for the input. I went and looked at these. I was very impressed with the olson. The other one I felt was pretty cheap. I went and bought the olson. I hadn't seen this post. I think I still would have bought the olson for two reasons. One it is local and I could see it and touch it. The other is the harbor freight 20% super coupon. So it wasn't $70, but $56. I doubt it could be beat for that price. 

The olson has a very good feel about it. The valve is smooth. Yeah, the gages are not correct, but I don't use them for anything more than an indicator anyway. I'll need to get a 3/8 to 1/4 reducer bushing to mount the solenoid valve bubble counter to it, but that is super straight forward. I'll post pics in a bit.


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## jeffkrol (Jun 5, 2013)

Jcricket said:


> Hey Jeff,
> Thanks for the input. I went and looked at these. I was very impressed with the olson. The other one I felt was pretty cheap. I went and bought the olson. I hadn't seen this post. I think I still would have bought the olson for two reasons. One it is local and I could see it and touch it. The other is the harbor freight 20% super coupon. So it wasn't $70, but $56. I doubt it could be beat for that price.
> 
> The olson has a very good feel about it. The valve is smooth. Yeah, the gauges are not correct, but I don't use them for anything more than an indicator anyway. I'll need to get a 3/8 to 1/4 reducer bushing to mount the solenoid valve bubble counter to it, but that is super straight forward. I'll post pics in a bit.



Well you sort of missed the subtle point..
Flow regulators generally have a set pressure and control "flow"..
Think of it this way.. You have a normal regulator w/ adjustable psi feeding a "metering valve" ie a "flow control" device..


That's whats so odd about it..

Fortunately most "flow control" devices usually run at 30-50 psi..so I can't say it doesn't work but it's not exactly err.. "standard"..

All depends on what you want to feed it to..
This is kind of fun to explain the differences ..


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## jeffkrol (Jun 5, 2013)

Had to sit back and think about this a bit.. not sure how one would use constant pressure w/ a needle gauge to monitor flow...but it can be done..
https://www.orangeresearch.com/flow-meter-flow-gauges-manufacturer.php

But like I said flowmeters use a constant pressure and just change flow..

OK found a suitable answer.. sort of a 3rd type, this explains the 2 flow types..:


> the difference is with a flow METER pressure is one of the constants, a flow GUAGE uses orfice size as a constant. think of it like this:
> a) gas density, a constant for both (argon in this case)
> b) orifice area, constant in FG, variable in FM
> c) pressure, variable in FG, constant in FM
> ...





> The top unit will show by setting the pressure on one side of a calibrated orifice and having the pressure gauge calibrated to the PRESUMED flow for that pressure.





> A certain pressure through a fixed hole size will produce a fixed flow rate.


Now you made me go learn something.. 

OK the basics are taken care of.. Now.. Whats the pressure??

OK a possible answer.. going a bit backwards:


> If you buy and install the folowing parts onto your regulator it will be converted to a flow gage regulator. Only worth doing if regulator is rated for 3000psi inlet pressure, is in good shape with no regulator pressure creep and can smothly adjust regulated outlet pressure from 0 to 50 psi.
> 
> Flow gauge to replace your regulator's LP pressure gauge and regulator outlet fitting with orifice that matches requirement of flow gauge.


So you should be good to replace the weird flow gauge w/ a 0-100psi pressure gauge (or check it by hand via outlet pressure test and use the orig gauge.)

side note:
Inside that regulator is an orifice (restriction) w/ the possibly following size(s)


> Typically the Smith flow gauges require a .032 orrifce. The Harris .036-.037


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## Jcricket (Nov 30, 2018)

Hey Jeff,
I read and re-read your post. I am going to have to read it a few more times and get some base knowledge I am missing to understand it all. But I will do it. 

Here was my thinking, and it is quite possibly wrong. 
The bubble counter is a flow meter of sorts. The regulator will simply adjust the PSI. I intend to put the solenoid valve and the bubble counter after the regulator. This should give me "better" or more sensitive control of the co2 delivered to the tank. Or at least this is my thinking. I think this will also give me some control over another variable. That would be the back pressure or pressure in the delivery line. Depending on what method of delivery for the co2(diffuser vs reactor) the flow can greatly be affected. A variable pressure could possibly overcome the restriction. Feel free to laugh out loud and tell me I am nuts. Most of what I just typed is an intuitive guess.


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## AguaScape (Oct 28, 2018)

I highly doubt that you will get enough flow control from those regulators without a more precise needle valve. Those orifice sizes are way to large for a planted tank. My 2 cents. Probably not worth much more.


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## jeffkrol (Jun 5, 2013)

Jcricket said:


> Hey Jeff,
> The bubble counter is a flow meter of sorts.


more correctly 1/2 of a flowmeter. Like a guage is part of a regulator..




Jcricket said:


> The regulator will simply adjust the PSI.


Yes, but you don't know what the psi is (well knowing the gas and exact orifice size one could calculate what flow equals what pressure, but err messy).




Jcricket said:


> I intend to put the solenoid valve and the bubble counter after the regulator. This should give me "better" or more sensitive control of the co2 delivered to the tank. Or at least this is my thinking. I think this will also give me some control over another variable. That would be the back pressure or pressure in the delivery line. Depending on what method of delivery for the co2(diffuser vs reactor) the flow can greatly be affected. A variable pressure could possibly overcome the restriction. Feel free to laugh out loud and tell me I am nuts. Most of what I just typed is an intuitive guess.


Still need a metering valve .. second part of the "flowmeter"


My biggest concern was pressure and if adjustable. it is..
Next is what "is" the pressure. 

Atomizers use like 25-35psi
Reactors can go as low as about 10psi.


IF in theory you max out at 50psi. not an issue as long as one doesn't crank it full. 50-ish psi it a bit risky....
If you use an atomizer you just slowly open the reg till you get bubbles out (metering valve open quite a bit at this point, will adj 'bubble rate"
once you get good flow)..and maybe a tweak more.
Will have to do a bit of trial and error anyways because there are some(minor) pressure losses in the solenoid and metering valve (needed AFAICT)..
I know I'd change the gauge out.. $10-ish purchase on eek bay..maybe even at some local stores..
*THEN again *it may not be possible. What is troubling is, if you look at the manual it states* "no replacement parts are available"* makes me nervous about thread types..
or if they used something like permanent loc tite..

don't forget check valves..


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## Jcricket (Nov 30, 2018)

I'll find a different gage and swap it out then. I was wondering about he psi for the diffusers. I'll post more when I get this done.


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## Jcricket (Nov 30, 2018)

pic ass promised









changed the gauge ot a 0-100 pis. Adjusted the psi to 30 and the setup works beautifully. I have dropped the ph about .6 in 5 hours of use. I'll need to tweak it a bit I am sure, but it seems far more precise and sensitive to adjustment now.


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## jeffkrol (Jun 5, 2013)

Jcricket said:


> pic ass promised
> 
> 
> changed the gauge ot a 0-100 pis. Adjusted the psi to 30 and the setup works beautifully. I have dropped the ph about .6 in 5 hours of use. I'll need to tweak it a bit I am sure, but it seems far more precise and sensitive to adjustment now.





YEA!!!

Any idea of the max out pressure you can get?
No don't blow up your system...


As long as it gets near 50 it's good for anything..


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## Jcricket (Nov 30, 2018)

No, not yet. I dialed it up to 40 to start then backed it down. 
My first regulator was so bad it leaked out a 5lb tank of co2 in about 3 days. It was leaking around the front of the regulator, where a knob would be if it were adjustable. I am on empty now. Tomorrow, I'll get a fresh tank and see what I can do.


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## ChrisX (May 28, 2017)

Jcricket said:


> pic ass promised
> 
> 
> 
> ...


Is there a needle valve or are you controlling flow by adjusting pressure? If the latter, my concern is that over time the flow will change as the tank depletes.


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## Jcricket (Nov 30, 2018)

ChrisX said:


> Is there a needle valve or are you controlling flow by adjusting pressure? If the latter, my concern is that over time the flow will change as the tank depletes.


The picture shows the silicone tubing attached to a bubble counter. That is on a needle valve which is screwed into a solenoid valve. I would bet that the flow rate will change as the pressure changes - that is a given. However, I would think that would only happen once the tank is near empty. That is a guess on my part, but an excellent question.


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## ChrisX (May 28, 2017)

Jcricket said:


> The picture shows the silicone tubing attached to a bubble counter. That is on a needle valve which is screwed into a solenoid valve. I would bet that the flow rate will change as the pressure changes - that is a given. However, I would think that would only happen once the tank is near empty. That is a guess on my part, but an excellent question.


If this doesn't work out for you, I got one of those Chinese regulators from ebay for $50 which has been consistently good for going on two years. It came with solenoid, bubble counter, and needle valve, although the pressure is fixed.


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## Jcricket (Nov 30, 2018)

ChrisX said:


> If this doesn't work out for you, I got one of those Chinese regulators from ebay for $50 which has been consistently good for going on two years. It came with solenoid, bubble counter, and needle valve, although the pressure is fixed.


That is what I just replaced. IT was awful. The bubble counter varied speed as you watched it. The unit leaked co2. Clearly it was defective. I think I have about $75 in this one.


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## Little Soprano (Mar 13, 2014)

While the needle valve is a little finicky, Blueprint (hydroponic company) makes an _excellent_ regulator for $85.00. It is, unfortunately, permanently set at ~40psi working pressure, but the regulator works like a charm, comes with a solenoid, and once I would set it, it never wavered. I would probably add a different needle valve if I got it out of storage to use again, but I'll come right out and say it held its bubble count as good as my GLA Pro SS-1 once it was set. Only thing I didn't like, at the time, was not having a bubble counter on the regulator, but now that I use a tank where a bubble counter is useless, it doesn't matter too much. 

https://www.nwgsupply.com/products/...nDF9MHqKHILzHfKwbL8bQd1GmuFDKgahoCQQwQAvD_BwE


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## Rush3737 (Jan 15, 2013)

Little Soprano said:


> While the needle valve is a little finicky, Blueprint (hydroponic company) makes an _excellent_ regulator for $85.00. It is, unfortunately, permanently set at ~40psi working pressure, but the regulator works like a charm, comes with a solenoid, and once I would set it, it never wavered. I would probably add a different needle valve if I got it out of storage to use again, but I'll come right out and say it held its bubble count as good as my GLA Pro SS-1 once it was set. Only thing I didn't like, at the time, was not having a bubble counter on the regulator, but now that I use a tank where a bubble counter is useless, it doesn't matter too much.
> 
> https://www.nwgsupply.com/products/...nDF9MHqKHILzHfKwbL8bQd1GmuFDKgahoCQQwQAvD_BwE


 @Greggz, I'm curious, would something like the regulator above seem like a good fit with the Dwyer flowmeter to be a somewhat complete CO2 system? Seems like the regulator is more solid than most of the cheap aquatic ones online, and if you use the Dwyer then the lack of a bubble counter is not an issue. Biggest concern is if the constant working pressure is enough for our use, for which I honestly have no clue. 

If it is then I think this and the flowmeter would be a great ~$150 setup for someone to try in the future.


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## Little Soprano (Mar 13, 2014)

Rush3737 said:


> @*Greggz*, I'm curious, would something like the regulator above seem like a good fit with the Dwyer flowmeter to be a somewhat complete CO2 system? Seems like the regulator is more solid than most of the cheap aquatic ones online, and if you use the Dwyer then the lack of a bubble counter is not an issue. Biggest concern is if the constant working pressure is enough for our use, for which I honestly have no clue.
> 
> If it is then I think this and the flowmeter would be a great ~$150 setup for someone to try in the future.


Well I have both. Could always do an experiment. I have a Dwyer and the reg above. I have a Cerges running on my 120g, and my regulator is set at 40psi working pressure anyway, which is somewhat ironic that I spent $$$ on my GLA versus the cheaper Blueprint CO2 reg I bought at my local hydroponics place.


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## Rush3737 (Jan 15, 2013)

That would be awesome if you could test that, my thinking is as follows:

People are told they have two options for CO2
A. Cheap and simple packs from China with reg/sol/needle/bubble all together and ready to go. 
B. Expensive and precise builds with all those options and perhaps a flowmeter.

If this works it could be a great middle ground for the ~$150. When it comes right down to it all people needs is a regulator that gets CO2 from the tank, a solenoid for a timer, and a reliable way for the correct amount of CO2 to run when the solenoid is open. If that reg/dwyer combo fills all that, and does it with high quality long lasting parts I think it would be a standout combination for people going forward.


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## Greggz (May 19, 2008)

Rush3737 said:


> @Greggz, I'm curious, would something like the regulator above seem like a good fit with the Dwyer flowmeter to be a somewhat complete CO2 system? Seems like the regulator is more solid than most of the cheap aquatic ones online, and if you use the Dwyer then the lack of a bubble counter is not an issue. Biggest concern is if the constant working pressure is enough for our use, for which I honestly have no clue.
> 
> If it is then I think this and the flowmeter would be a great ~$150 setup for someone to try in the future.


You know that might be a good combination. 

If you are running into a reactor, you really need very little pressure. I run mine at about 15psi, but really for no particular reason. I would guess running constantly at 40psi should not be an issue.

When I got started, I bought a GLA system. When I began using it, I quickly realized the bubble counter was pretty much useless at my flow rate. That's when I started searching for better solutions, and ended up going with the Dwyer. Had I had known then what I know now, I would have went with something like above, and just bought an inexpensive regulator and flow meter.

And that's not to say the GLA is bad. I've been very happy with the unit as a whole. But with the flow meter you can get by with a lot less. Really no need for bubble counter or needle valve.


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## Rush3737 (Jan 15, 2013)

My biggest issue is right now I can't find any reviews for this particular regulator online. There are two cheaper knockoff versions on Amazon but no clue if they are a quality representation of the Blueprint version. Still, for the simplicity of the created system if LS tries this and it works I may very well grab one and sell my current regulator.


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## jeffkrol (Jun 5, 2013)

Greggz said:


> And that's not to say the GLA is bad. I've been very happy with the unit as a whole. But with the flow meter you can get by with a lot less. Really no need for bubble counter or needle valve.



not to argue the point, but I think there is sort of a misunderstanding here..


Flowmeter is a floaty ball w/ a Fabco equiv metering valve (Well w/ Dwyer, no guarantees on cheaper flowmeters )


So nothing really changes...and regulators would still "matter"....

Each method has its niche..


One could say you have def more "visualization" of any changes (subtle or not so subtle) so there is that..
and an idea of ACTUAL flow
but it is still mostly equivalent to a metering valve/bubble counter..


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## Greggz (May 19, 2008)

jeffkrol said:


> One could say you have def more "visualization" of any changes (subtle or not so subtle) so there is that..
> and an idea of ACTUAL flow
> but it is still mostly equivalent to a metering valve/bubble counter..


Jeff this is where I think you are missing it.

Trying to adjust relative flow in a larger tank (large tank being key) is nearly impossible with a metering valve/bubble counter.


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## jeffkrol (Jun 5, 2013)

Greggz said:


> Jeff this is where I think you are missing it.
> 
> Trying to adjust relative flow in a larger tank (large tank being key) is nearly impossible with a metering valve/bubble counter.



No I well understand that.. Has nothing to do w/ what I was referring to..
Not sure what I can do to explain it better.. 





> But with the flow meter you can get by with a lot less. Really no need for bubble counter or needle valve.


Maybe I'm misunderstanding what you were trying to say here..
bubble counter/metering valve vs flowmeter and valve are *functionally equiv..* 
This is strictly referring to what they are, not what each is good or bad for..

No more no less..
Picking one over the other is a matter of which "system" works best for a tank and you..


Tell me what do you call that knob that controls the flow??
It's a metering valve..because it doesn't LOOK like a Hoke, or swaglok doesn't mean its not functionally equiv. to it..


sometimes I think you just don't want to understand my words..


> *The Compact Series OMA Oxygen Flowmeter *is made especially for medical applications and manually controlling flow from oxygen generators. Flow levels are kept stable by precision valve and knob adjustment. The low cost flowmeter is made from durable clear acrylic plastic. They easy-to-read scale is hot stamped into the acrylic so it will not wear off. The ball float is highly visible against the light blue background. Readings are repeatable within ±4% full scale accuracy.





> Each method has its niche..


maybe I should have expanded that a bit..


> When you get to a tank of a certain size, bubble counters are basically unusable. You can't count a stream of bubbles. And with the best metering valve, once it is bumped, or you change the tank, how do you dial it back in?


What size tank was Rush3737 referring to in post #20?
Large or small?


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## Little Soprano (Mar 13, 2014)

Rush3737 said:


> That would be awesome if you could test that, my thinking is as follows:
> 
> People are told they have two options for CO2
> A. Cheap and simple packs from China with reg/sol/needle/bubble all together and ready to go.
> ...


What I have learned, is the hydroponics billed equipment is just as good quality wise than "aquarium" billed equipment, for a quarter of a price. It's like bulbs and T5 set ups. You can get T5 set ups with excellent reflectors for a _fraction_ of the price of aquarium set ups. On amazon, you can get a 6 pack of the sunblaster T5HO strips with the individual Nano Tech reflectors and 6400K bulbs for $270.99 - shipped for free. And they offer spectacular flexibility in regards to how many lights you want in a bank, 1, 3, 6 its up to you. Aquarium units are expensive, for pretty much the same thing. 

That regulator worked like a charm, and still does. It's a heavy regulator, nothing on it, to me, feels cheap. Even the tubing that came with it was very thick and sturdy CO2 tubing. And 25' of it none the less. At the time I didn't like it because on a 40g tank a needle valve does need to be very very precise. On this tank now I don't care about if my needle valve can adjust my CO2 bubble by bubble, its not relevant to a large tank. A _reliable_ needle valve/regulator that keeps steady is important - which this one did just fine. My GLA regulator I adore, if just for the customer service when I screw things up, but that grow regulator is still as good as when I bought it 6 years ago.


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## Jcricket (Nov 30, 2018)

Hey Folks,
About how long should a five pound tank of CO2 last in a 75 gallon tank? I have read it should be good for several months. Any feedback on this?

Bump: Hey Folks,
About how long should a five pound tank of CO2 last in a 75 gallon tank? I have read it should be good for several months. Any feedback on this?


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## jeffkrol (Jun 5, 2013)

Jcricket said:


> Hey Folks,
> About how long should a five pound tank of CO2 last in a 75 gallon tank? I have read it should be good for several months. Any feedback on this?



20# of CO2 is approx 4,950,000 cc of gas. I just picked one I found YMMV



> _For my 65 gal tank I have it set at 15cc/min and for the 135 gal it is set at 25cc/min_



5# tank has 1,237,500 CC's of CO2..


at 8 hrs/day and the above rate 15cc/minute (7200cc/day)


171 days....


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## Jcricket (Nov 30, 2018)

jeffkrol said:


> 20# of CO2 is approx 4,950,000 cc of gas. I just picked one I found YMMV
> 
> 
> 
> ...


I must have a leak somewhere. It lasted about two days at 7 hours per day. My ph dropped about .7 each day, so it is not absorbed into the water. Also, the water surface has almost no co2 bubbles reaching it. Time for some trouble shooting...................


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## Jcricket (Nov 30, 2018)

Hey Jeff,
What do you recommend for a flow rate for a 75 gallon tank. The 15cc/min you posted above? Also, how do you "regulate" or measure your flow? Is there a flow meter you recommend?
Thanks for the help thus far.


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## Greggz (May 19, 2008)

Many here with larger tanks (55+) use a Dwyer flow meter. The model RMA151-SSV is generally a good scale for a 75G tank. 

There is a discussion in my journal about them here..........................

https://www.plantedtank.net/forums/12-tank-journals/1020497-greggz-120g-rainbow-fish-tank-new-bows-12-27-18-a-66.html#post10821809

Many successful folks here very happy with them. It's a big improvement over needle valve/bubble counter. 

As to initial flow rate, hard to say. Most 75G's are somewhere between 25 & 40 cc/min. Much depends on your particular tank.

Hope that helps.


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## Jcricket (Nov 30, 2018)

Greggz said:


> Many here with larger tanks (55+) use a Dwyer flow meter. The model RMA151-SS is generally a good scale for a 75G tank.
> 
> There is a discussion in my journal about them here..........................
> 
> ...


Hey Gregg, this helps a lot. I would imagine the method of adding co2 to the tank would affect the flow rate. A diffuser might use less than a reactor or vice versa. I'll get me one of these flow meters and then adjust accordingly.
Thanks again!!!!!!!!!!


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## Joshism (Nov 26, 2015)

I'm not sure if it has been discussed, but how well does the flow meter handle EOTD?


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## Jcricket (Nov 30, 2018)

Joshism said:


> I'm not sure if it has been discussed, but how well does the flow meter handle EOTD?


EOTD? I am still a bit of a newbie. What is that acronym?


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## AguaScape (Oct 28, 2018)

EOTD = End Of Tank Dump. A large increase of CO2 flow through the regulator when the pressure from the tank drops below a certain level. More commonly happens with single stage regulators, but there are reports of it even happening with a two stage.


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## Jcricket (Nov 30, 2018)

Question for you regulator gurus
I think I might have a small leak. If I shut down the output of the regulator, in other words no flow to the aquarium, and then charge the regulator by opening the co2 tank I get a reading of ~700 psi on the high pressure gauge. This is good. However, if I leave it in this state for lets say an hour or two, the ~700 psi drops to zero. A leak? 

I tried the same with the low pressure gauge and it hold steady at whatever pressure I give it. I figure it has to be on the high pressure or inlet side. So the connections to the tank, or the gauge itself. Thoughts? Where and how would you look for the leak?


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## jeffkrol (Jun 5, 2013)

My usual suspect is not tight enough at tank to reg (CGA nut).
You can spray soapy water on it and watch for bubbles..
Can't find internal gauge leaks w/ this though.

Gauge, guage threads, cga seal main 3..


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## Jcricket (Nov 30, 2018)

I'll give it a good look over and see what happens. I'll try the soapy water on all the threads and see if it shows anything. If not, then I would guess it must be the gauge.


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## pfarris (Aug 7, 2013)

I bought a harbor freight co2 regulator, and it has killed my fish 3 times. As soon as it get the tank gets close to empty it would dump the rest of the co2 into my tank killing all my fish. I dont understand, even with a decent needle valve, it still happened. For the time, and money on fish lost I could of bought a dual stage unit.


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## Jcricket (Nov 30, 2018)

pfarris said:


> I bought a harbor freight co2 regulator, and it has killed my fish 3 times. As soon as it get the tank gets close to empty it would dump the rest of the co2 into my tank killing all my fish. I dont understand, even with a decent needle valve, it still happened. For the time, and money on fish lost I could of bought a dual stage unit.


which unit did you buy and how long ago was that?


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## Cichlid-140 (Sep 28, 2018)

pfarris said:


> I bought a harbor freight co2 regulator, and it has killed my fish 3 times. As soon as it get the tank gets close to empty it would dump the rest of the co2 into my tank killing all my fish. I dont understand, even with a decent needle valve, it still happened. For the time, and money on fish lost I could of bought a dual stage unit.


It has to do with the reg not the needle valve. Single stage regulators that are specifically designed for planted tank use will often have pressure reliefs that break at ~50 psi (I believe I read that GLA's will break at between 52 and 54 psi). Other regulators normally have pressure reliefs that break between 100 and 200 psi and above (my old Victor two Stage broke at 400 psi). Considering the 30 psi minimum for a ceramic "Atomic" style diffuser (with two exceptions that's all GLA sells) and a more probable pressure of 35 psi, 50 psi isn't a big jump. The really low cost fixed output regs are usually set at the factory at between 40 and 45 psi making the end of tank offset even less. So, unless you set your CO2 levels on the bleeding edge of tolerance for your livestock the change will probably not be particularly harmful.

Can't say that for welding single stage units.


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## Jcricket (Nov 30, 2018)

Cichlid-140 said:


> It has to do with the reg not the needle valve. Single stage regulators that are specifically designed for planted tank use will often have pressure reliefs that break at ~50 psi (I believe I read that GLA's will break at between 52 and 54 psi). Other regulators normally have pressure reliefs that break between 100 and 200 psi and above (my old Victor two Stage broke at 400 psi). Considering the 30 psi minimum for a ceramic "Atomic" style diffuser (with two exceptions that's all GLA sells) and a more probable pressure of 35 psi, 50 psi isn't a big jump. The really low cost fixed output regs are usually set at the factory at between 40 and 45 psi making the end of tank offset even less. So, unless you set your CO2 levels on the bleeding edge of tolerance for your livestock the change will probably not be particularly harmful.
> 
> Can't say that for welding single stage units.


When you say break, does that mean wide open? I have set my regulator to about 15psi on the low side. I then have a dwyer flow meter set to about 20cc. II I am using a home built griggs reactor. So far it seems to be functioning exceptionally well, besides the small leak I am still chasing. I don't see how a regulator can open up and "dump" with the low pressure being set at 15psi.


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## jeffkrol (Jun 5, 2013)

most one stage regs creep up in pressure at the end of the tank:
https://www.harrisproductsgroup.com/en/blog/2017/april/single-stage-regulator-delivery-pressure.aspx

There is a formula to estimate the pressure rise (supply pressure effect)
So depending on multiple factors this can cause a large spike in CO2 delivery in a short period of time..
your tank stays stable at like 700psi (variable) till all the liq. CO2 is gone. After that the pressure will drop (slowly or rapidly ) depending on delivery. 


> With supply pressure effect, there is an inverse reaction on the outlet pressure to a change in inlet pressure. For example, when the inlet pressure decreases the outlet pressure increases. Conversely, when the inlet pressure increases the outlet pressure decreases.


I'll have to find the formula though..



> In a typical single stage regulator the supply pressure effect may be about 1%, so a 2000 psig decrease in inlet pressure would result in a 20 psig (1% of 2000 psig) increase in outlet pressure.
> In a typical two stage regulator, the supply pressure effect is approximately .01%. The 2000 psig decrease in inlet pressure to the first stage regulator would result in a 20 psig (1% of 2000 psig) increase in outlet pressure. That increase would be a 20 psig increase to the inlet of the second stage pressure regulator resulting in a 0.2 psig (1% of 20 psig or .01% of 2000 psig) decrease in outlet pressure.


May not seem like a lot but can mean a lot depending on your working CO2 levels..And different regulators have different %'s
In your case the psi out can go up 8psi.. based on the 1% figure (800 x .01 = 8)
50% increase in outlet pressure..
so ..actually.. at lower pressures this means more.. If you were running 40psi and went up to 48 may not be a big deal..

Then for whatever reason (related or not) some regs just fail at the end though most blame it on the needle valve for these.


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## Cichlid-140 (Sep 28, 2018)

Jcricket said:


> When you say break, does that mean wide open? I have set my regulator to about 15psi on the low side. I then have a dwyer flow meter set to about 20cc. II I am using a home built griggs reactor. So far it seems to be functioning exceptionally well, besides the small leak I am still chasing. I don't see how a regulator can open up and "dump" with the low pressure being set at 15psi.


By break I meant that the relief valve opens at a given pressure. The opening is abrupt not gradual, much like a break. When the pressure lowers below the value of the relief it closes. I hope that helps.

As for the dump, the Harris description was fine but it may be tough for some without a diagram.

2000px-Single-stage-regulator.svg by pat w1, on Flickr

When the regulator comes to rest at a particular adjustment it does so because an equilibrium of a total of 4 forces is established. All of these forces act upon the diaphragm. On one side is the force of the adjustment spring. On the other is the force of the poppet post pressing against the center hardpoint and the force of the pressure of the gas pressing against the diaphragm. The pressure from the poppet post is a combination of two forces. One is the poppet spring and the other is the force from the inlet gas pressure against the bottom of the poppet stopper. Once the pressure is set and the handle isn't moved the two springs are effectively exerting constant pressure. Assuming the inlet pressure remains constant there is only one pressure that will equalize the forces and allow the poppet to close. This is the force of the gas pressing against the diaphragm. As gas is used the outlet pressure goes down taking the system out of equilibrium and the poppet re-opens allowing more gas in to again equalize the system.

The dump occurs when the inlet pressure reduces at the end of the bottle and exerts less pressure against the poppet stopper. That part of the system is no longer at the equilibrium point for the desired outlet pressure. That reduction allows the poppet to open, allowing more gas in, resulting in enough added gas pressure against the diaphragm to offset the reduction in the pressure on the back of the poppet. This added gas pressure is what is delivered to the outlet which we call a dump.


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## Jcricket (Nov 30, 2018)

Cichlid-140 said:


> By break I meant that the relief valve opens at a given pressure. The opening is abrupt not gradual, much like a break. When the pressure lowers below the value of the relief it closes. I hope that helps.
> 
> As for the dump, the Harris description was fine but it may be tough for some without a diagram.
> 
> ...


Excellent post. Now I understand how the regulator works as well. Is there any way to safe guard against the EOTD?


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## jeffkrol (Jun 5, 2013)

Jcricket said:


> Excellent post. Now I understand how the regulator works as well. Is there any way to safe guard against the EOTD?











Replace your CO2 tank before it empties..
First sign of a noticeable (not due to temp changes) drop of pressure..
Or use a 2 stage..


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## Cichlid-140 (Sep 28, 2018)

Jcricket said:


> Excellent post. Now I understand how the regulator works as well. Is there any way to safe guard against the EOTD?


Most think they are being frugal by taking the tank down to near zero pressures before refilling. This is wrong thinking. After you get a bottle filled the majority of the CO2 is in a liquid state and the pressure is dictated by the temp usually between 800 & 900psi. Once the pressure drops below ~600psi it's all in a gaseous state. None of it is liquid. If you will refill some time before the tank gets below - say 300-400 psi you'll avoid most of the hazard. The GLA regulators have a red "Order Gas" zone on their output gauge that covers anything below 500psi. Other than that pay the premium for a two stage regulator.


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## Jcricket (Nov 30, 2018)

Greggz said:


> Many here with larger tanks (55+) use a Dwyer flow meter. The model RMA151-SSV is generally a good scale for a 75G tank.
> 
> There is a discussion in my journal about them here..........................
> 
> ...


Edit: I think this is being answered in the dwyer flow meter thread being discussed currently

Hey Folks,
I have my system up and running. I ran into issues mounting the griggs reactor so that has been delayed. I went back to the difuser. With the flow valve set at 15cc/min, the difuser was crazy full of bubbles. I turned it down to 10cc, which seemed more appropriate. The ph in the aquarium dropped 1ph in about 2.5 hours. I felt that was pretty scary. I now have it set at something like 2cc/min. It is hard to tell as the gauge is not incremented into that fine of a dial. 

ph went from about 7.3 to 6.6
kh is 4
this puts co2 at about 30ppm - entering the too high danger zone. I shut off the co2 for now. Tomorrow I will try and start at 2cc/min and see what happens.


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## Cichlid-140 (Sep 28, 2018)

Jcricket said:


> Edit: I think this is being answered in the dwyer flow meter thread being discussed currently
> 
> Hey Folks,
> I have my system up and running. I ran into issues mounting the griggs reactor so that has been delayed. I went back to the difuser. With the flow valve set at 15cc/min, the difuser was crazy full of bubbles. I turned it down to 10cc, which seemed more appropriate. The ph in the aquarium dropped 1ph in about 2.5 hours. I felt that was pretty scary. I now have it set at something like 2cc/min. It is hard to tell as the gauge is not incremented into that fine of a dial.
> ...


Not necessarily valid. The conversion is dependant on the KH coming only from carbonate. If other buffers ar present (ie. phosphate) then they would need to be subtracted from the measured KH to have a more valid carbonate component for KH. The equation places the *[STRIKE]carbonate KH[/STRIKE] (wrong - my bad should be pH)* as a factor in the exponent of 10.

((12.839*dKH)*(10^(6.37-pH))) or
((15.65*dKH)*(10^(6.35-pH)))
both have been argued as correct. I use the first.

That's why we shoot for a drop of ~1.0. Under non injected conditions the CO2 dissolved in water is in an equilibrium state with the air. Currently that places the concentration at ~3ppm once the CO2 is off gassed and allowed to settle. From that point a drop in pH of 1.0 moves the calculated ppm by a factor of 10^1 or 10. 3x10=30 - 30ppm.

My guess is your carbonate dKH is closer to 2.0. You are only showing a 0.7pH drop. A rough calc puts that at ~15ppm.


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## Jcricket (Nov 30, 2018)

Cichlid-140 said:


> Not necessarily valid. The conversion is dependant on the KH coming only from carbonate. If other buffers ar present (ie. phosphate) then they would need to be subtracted from the measured KH to have a more valid carbonate component for KH. The equation places the *[STRIKE]carbonate KH[/STRIKE] (wrong - my bad should be pH)* as a factor in the exponent of 10.
> 
> ((12.839*dKH)*(10^(6.37-pH))) or
> ((15.65*dKH)*(10^(6.35-pH)))
> ...


Thank you for the input. I have been dosing with ferts this week. I am using the PPS with the salts from GLA. I am quite certain they have an affect on the kh. Very good point. 
Currently I have the pis before the flow meter set to 15psi and the flow meter to 2cc/min. This gives what I would consider to be an addequate bubble column. I got a late start so I didn't get a starting ph. Maybe tomorrow for that...............

Thanks again.


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## pfarris (Aug 7, 2013)

Im sorry for the late response. I haven't gotten any notifications?? I bought a harbor freight co2 regulator about 5 years ago, and it was for welding. The end of tank dump happened every time my cylinder ran out. It was a chicago brand I think. So like the other guys said, if your flow meter, or needle valve is set for a certain bubble count or flow rate at X psi, when the end of tank pressure exceeds that psi so does the flow through your needle valve or flowmeter. I just bought a dual stage from aquariumcoop.com Its currently running now, and seems to be holding steady pressure, keeping my fingers crossed.


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## ChrisX (May 28, 2017)

pfarris said:


> Im sorry for the late response. I haven't gotten any notifications?? I bought a harbor freight co2 regulator about 5 years ago, and it was for welding. The end of tank dump happened every time my cylinder ran out. It was a chicago brand I think. So like the other guys said, if your flow meter, or needle valve is set for a certain bubble count or flow rate at X psi, when the end of tank pressure exceeds that psi so does the flow through your needle valve or flowmeter. I just bought a dual stage from aquariumcoop.com Its currently running now, and seems to be holding steady pressure, keeping my fingers crossed.


I have been using one of these cheap ebay regulators and there did not appear to be any EOTD.


[Ebay Link Removed] < The JL Aquatic ones that come in green box.

The needle valve adjustment is fiddly, but once set is constant. Probably best value in cheap regulators. These are all MIC, not sure spending more for a "mid range" one has any value.


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