# Need help with Rex Grigg type reactor with a FX5



## PUNISHER VETTE (Jan 26, 2009)

So I've built many Rex type reactors and not many have been successful for me. I think the Fluval FX5 filter has just too much flow as well as me not designing them to what i needed.

I did how ever make the mistake of going larger in diameter instead of longer which i know know i should be doing.

Can anyone with an FX5 let me know how you built yours or if you have pictures so i don't waste more money building a reactor that just has the CO2 pop out the outlet.

I was thinking 2 or 3" x at least 3ft or so with possible things in it to break up any bubbles.


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## tazcrash69 (Sep 27, 2005)

I don't have an FX5, but why not just plumb in a bypass?
Split the line, put a valve to control flow, then either combine back, or use 2 outputs?


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## PUNISHER VETTE (Jan 26, 2009)

tazcrash69 said:


> I don't have an FX5, but why not just plumb in a bypass?
> Split the line, put a valve to control flow, then either combine back, or use 2 outputs?


That's not a bad idea and wouldn't be too hard. Slightly more risk of a line popping off but nothing too bad.

I'd have to see if any local stores have a splitter that i would need...in the FX5 size which i believe is 1" or something close to that.

Now if i did make a Rex Grigg reactor does the CO2 enter the bottom or the top? I've always put it at the top but have seen it done differently and didn't know what's right/wrong.

And the longer i make it the better right? I know Rex designs his to about 20" but what if i double that couldn't i get that much more diffusion?


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## wakesk8r (Nov 26, 2007)

I run mine on a marine land c220 220gph.
My reactor is 20 inches long and 2" pipe
the co2 enters about a 3rd of the way up. so it is closer to the bottom
Alot of people mount them at an angle to increase diffusion
if you mount it at an angle be sure your output is facing down! the bubbles will have a harder time getting out


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## PUNISHER VETTE (Jan 26, 2009)

blue-ram said:


> I run mine on a marine land c220 220gph.
> My reactor is 20 inches long and 2" pipe
> the co2 enters about a 3rd of the way up. so it is closer to the bottom
> Alot of people mount them at an angle to increase diffusion
> if you mount it at an angle be sure your output is facing down! the bubbles will have a harder time getting out


The output of CO2 or of the reactor?

If it's the CO2 by facing down that means it's on top of the reactor right?

Now in the past i've had a 1/4" barbed end that i screw into the side of the reactor for easy on/off access. Do you think this was a bad?
Here's a picture of one i had built a long time ago....probably don't even have it assembled anymore.








as you can kinda see the barbed end is near the top in this old design. I guess i could have switched ends but...


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## wakesk8r (Nov 26, 2007)

the out put of the water needs to point down.
from your pic the co2 input seems a little high up. A lot of people put it near the top.
I figure the further down the longer the bubbles have to dissolve.
Those brass fittings are a bad idea if yo plan on shrimp.
I think you could probably just flip it over and it should work.
i don't have time to post a pic of mine but i will do it when i get home from work


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## Gatekeeper (Feb 20, 2007)

blue-ram said:


> the out put of the water needs to point down.
> from your pic the co2 input seems a little high up. A lot of people put it near the top.
> I figure the further down the longer the bubbles have to dissolve.
> Those brass fittings are a bad idea if yo plan on shrimp.
> ...


Why flip it over? That reactor looks fine to me. Inflow connects to top, outflow to the bottom. If you are getting CO2 leaking out of the bottom and into the outflow, then you need to slow down the amount of CO2 you are adding, add turbulence to the reactor (like bio balls or something), or do something like Walter said above and run a bypass. Nothing wrong with making the diameter bigger too.

These reactors are not rocket science. Don't over do it.


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## PUNISHER VETTE (Jan 26, 2009)

I think i'll try and make this reactor the same but in a 3" and slightly longer.

I'll also connect the CO2 more near the bottom. i always figured if it was near the top they'd have the longest way to go to dissolve. But that's the opposite by your reasoning and obviously mine hasn't worked so well so far.

I think no matter what i do I'll have to reduce the flow of my filter anyway as it's just too powerful. I think water is just going to be skyrocketing out with bubbles no matter how well i design it.


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## Gatekeeper (Feb 20, 2007)

? So your going to put it closer to the bottom even though you have already stated that the reactor is not providing sufficient contact time for the CO2 to dissolve???? Now your going to decrease it even more????

Think about the process before you rebuild it. I think the by pass loop hsa been the best advice so far...


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## PUNISHER VETTE (Jan 26, 2009)

gmccreedy said:


> ? So your going to put it closer to the bottom even though you have already stated that the reactor is not providing sufficient contact time for the CO2 to dissolve???? Now your going to decrease it even more????
> 
> Think about the process before you rebuild it. I think the by pass loop hsa been the best advice so far...



All the pictures of working ones i've seen here as well as people suggest putting it more near the bottom so the bubbles can float up.
I on the other hand I have never done that as i figured my filter was too powerful and they would just get pushed out faster. So far my way hasn't worked too well so maybe doing it their way will result in a success?

I also think adding bioballs inside will help reduce flow as well as break up the bubbles. They say they don't need it but when i've got this much flow i don't see why not.


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## fshfanatic (Apr 20, 2006)

My CO2 goes into the bottom. However, I dont have it plumbed into my FX5. The flow from the FX5 might just push the bubbles right out of the reactor. If you are not getting the amount of co2 into your water, turn it up.


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## fshfanatic (Apr 20, 2006)

Heres mine:


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## PUNISHER VETTE (Jan 26, 2009)

Yeah. I think i'll build it
3" diamater, 24+ inches long, co2 going in near the bottom.

IF my FX5 seems to be too powerful i'll just have to look into splitting the lines. Have 1 slower flowing one route to the reactor and what ever is left bypassing.

Only problem is i don't know if they make a Y splitter with flow valves.

Only thing i can think of would be something for a garden hose but then i'd have to find a way to connect hoses to that.


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## wakesk8r (Nov 26, 2007)

bubbles flow up,
The further to the bottom you put the input the more contact time you have.
as long as the co2 input is not so close to the h20 output that it just blows out.
heres mine
View attachment 11768

if you turn yours upside down the h20 will come in from the top on the side instead of directly from the top. This will create a vortex smashing the co2 into smaller bubbles.

PM me if you need more advice. I have built a few of these.
Mine does NOT send small bubbles into the tank.
100% dissolved 2-3bps


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## PUNISHER VETTE (Jan 26, 2009)

blue-ram said:


> bubbles flow up,
> The further to the bottom you put the input the more contact time you have.
> as long as the co2 input is not so close to the h20 output that it just blows out.
> heres mine
> ...



But if bubbles float up then if i add them near the top wouldn't they still be floating near the top? No matter what i think the flow on my filter is too powerful so no matter where i inject the CO2 it'll get pushed out without diffusing.

I'm still going to try it your way but I have a feeling it can't help any more then reducing my flow.


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## wakesk8r (Nov 26, 2007)

that thing must have hella flow!
the bypass is probably best bet.
Someone had a good plan for one recently


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## PUNISHER VETTE (Jan 26, 2009)

blue-ram said:


> that thing must have hella flow!
> the bypass is probably best bet.
> Someone had a good plan for one recently



Yeah like i stated in a PM and i'll share for the others.

"607 U.S. gallons (2,300 liters)of water every hour"

And i don't have much in terms of media in it so it might even be quicker depending on how they test theirs.


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## jjp2 (May 24, 2008)

If you don't use the split return nossle, its flow is higher than the 607. I have the FX 5 on my 125. I have my CO2 Tee'd in to my return just before my 40W gamma UV. The gamma is 36 inches long and horizontally mounted. I do get some misting in the tank as well as dissolved CO2. I think my bps is 5-7.


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## PUNISHER VETTE (Jan 26, 2009)

Yeah. I'll be building this tomorrow so i need to get this straight.

Why have the bubbles go in the bottom? I know they would float up but if you inject them already at the top what's the difference?

At least that way if my flow is too strong it'll give them at least the length of the pipe to diffuse instead of just getting forced out.


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## jjp2 (May 24, 2008)

Here is a picture of my plumbing.

In the picture 1288.jpg, the ribbed hose is the intake, comes from the tank into the FX5. The clear reinforced hose is the outlet. It goes into a T (hiding behind the ribbed hose) were the CO2 goes in. This then goes into the Gamma UV shown in 1290.jpg going behind the fx5 and co2 tank (also shown in 1291.jpg). 1289.jpg shows the outlet of the UV going into another T where air enters at night. This is all 1 inch hose. It is then split into 2 3/4 hose's and returned to each end of the tank with the outlets pointing forward and toward the middle. My outlets are mid tank.


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## Jeff5614 (Dec 29, 2005)

Not to get off topic, but I like the power strip you have in your cabinet, John, I think I may have to try something similar.


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## jjp2 (May 24, 2008)

I found that power strip at Lowes. Its 4 ft long with 10 outlets spaced 4 inches apart. Best I could find to deal with all those timers other than going to a controller.


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## PUNISHER VETTE (Jan 26, 2009)

WOW!!! I must be losing my mind. I went out to my garage to inventory what parts I already had and what i may need to buy in order to build the reactor.

I actually found what i was going to build already assembled. I guess I built it right before giving up on my CO2 system. Obviously I was using it with the CO2 going in at the top but i can just flip it upside down.

I had also put in a screw in section because i put bioballs in there. This way if things get clogged i can unscrew everything and fix the problem. Apply a little not hardening thread sealant and tighten it back up and ta-da.


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## Gatekeeper (Feb 20, 2007)

That thing is a monster... very nice.


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## wakesk8r (Nov 26, 2007)

that should take care of it!!
DIY extreme


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## PUNISHER VETTE (Jan 26, 2009)

I still can't believe I already had the stupid thing built. It's like i mentally blocked it out of my mind or something.

Will O2 diffuse about the same as CO2 would?

I say that b/c i think i'll hook it up and put an air pump with a valve on it. try to get it so the bpm are low and see if the oxygen will diffuse.

My regulator isn't scheduled to get here till next Tuesday.


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## Gatekeeper (Feb 20, 2007)

No, takes alot more to diffuse O2. Nowhere near as simple as CO2.


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## original kuhli (Nov 28, 2006)

Here's a set of photos of my plumbing, flow is counter current (top to bottom), mine has the heater and ports for a number of things in it. Works fine, no bubbles to the tank.

http://www.plantedtank.net/forums/g...d-photos-before-after-replant.html#post590593


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## PUNISHER VETTE (Jan 26, 2009)

Okay. The regulator came today so I hooked everything up.

Like I suspected there are still TONs of bubbles that are coming out. I can reduce the flow of the filter at the pump by about a 1/3 which helps a lot but i'm guessing that isn't the best thing for my filter. Not to mention the less filtration i'll be getting.

So this weekend i'll find a way to split the lines.


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## Gatekeeper (Feb 20, 2007)

Tons of bubbles.... like how big? Small bubbles are not horrible.


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## PUNISHER VETTE (Jan 26, 2009)

With about 50%-75% flow



At 100%


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## original kuhli (Nov 28, 2006)

Not a single bubble through mine, pH responds quickly, but the bubbles make their way through some fairly complex plumbing prior to leaving the system.


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## tazcrash69 (Sep 27, 2005)

PUNISHER VETTE said:


> Like I suspected there are still TONs of bubbles that are coming out. I can reduce the flow of the filter at the pump by about a 1/3 which helps a lot but i'm guessing that isn't the best thing for my filter. Not to mention the less filtration i'll be getting.


Just to make sure.. you have the out of the filter going into the top of the reactor, out of the bottom, and up to the tank making a big loop?
(And [email protected] injected at the top)


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## PUNISHER VETTE (Jan 26, 2009)

tazcrash69 said:


> Just to make sure.. you have the out of the filter going into the top of the reactor, out of the bottom, and up to the tank making a big loop?
> (And [email protected] injected at the top)



out of filter, into top, out bottom and all the way up to my tall tank.

except co2 is going in at the bottom like others here pointed out. I'll try flipping it around and seeing if that helps anything at all.


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## houstonhobby (Dec 12, 2008)

Vette,

My FX5 blows small bubbles into my tank too, but I don't have a CO2 reactor in the line. My CO2 reactor is off in a far corner. I don't know if the small bubbles are O2, CO2, or just water vapor from cavitation, but your problem may be the FX5, not the CO2 reactor.

Thanks,
Rod


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## PUNISHER VETTE (Jan 26, 2009)

houstonhobby said:


> Vette,
> 
> My FX5 blows small bubbles into my tank too, but I don't have a CO2 reactor in the line. My CO2 reactor is off in a far corner. I don't know if the small bubbles are O2, CO2, or just water vapor from cavitation, but your problem may be the FX5, not the CO2 reactor.
> 
> ...



No. It's from CO2 and it's because the flow is too quick. My FX5 has zero bubbles when the CO2 isn't running.


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## original kuhli (Nov 28, 2006)

My gas flows in the top, water flows in the top and that works for me. That said, my FX5 flow is split into three via vall valves and is at a reduced rate. Basically, it is a bypass.


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## PUNISHER VETTE (Jan 26, 2009)

original kuhli said:


> My gas flows in the top, water flows in the top and that works for me. That said, my FX5 flow is split into three via vall valves and is at a reduced rate. Basically, it is a bypass.



Yeah. I can easily turn it the original way i had built it with the CO2 going in at top and see if that helps anything at all.

If not i'm just going to have to do a bypass.


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## original kuhli (Nov 28, 2006)

Could stuff some bioballs in there to break up the flow a bit and provide a place for the CO2 to get caught/dissolved.


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## tazcrash69 (Sep 27, 2005)

You could still plumb in that Bypass to slow flow in the reactor while keeping the rate up.


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## Gatekeeper (Feb 20, 2007)

I have been thinking about this a bit.

How long was that reactor going in those movies with all the bubbles???? Are you sure thats not O2 that is trapped in the reactor?
It does take a while to theoretically "prime" the reactor and release all the caught up air. 

The best way to get rid of it is to hook it up w/o CO2 running and let it go for a day or so. The O2 will work its way out. Then start pumping in CO2.

Or another option is to set up a bleeder, but that can be a PITA if your not careful.


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## jjp2 (May 24, 2008)

Those bubbles are larger than the CO2 Mist I get with my CO2 T'ed into the return line.


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