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Discussion Starter · #1 · (Edited)
My experience with the usual inline DIY reactor has not been satisfying. The bubbles escape the reactor when the flow is 110 gph, even if the reactor is 1-1/2 ft. long and a limestone is used to inject the gas in the reactor.

The following reactor is using a strong circular water motion to disolve the CO2. The only commercial CO2 reactor that I know of that uses the same principle and no powerhead is internal and fails to work well with high flow rate and high bubble rate.

Here are some pictures:
http://www.aquaticplantcentral.com/gallery/showimage.php?i=1164
and click "Next picture" to see the progression.

The reactor is external, inline, and it's meant for very high flow rates. I'm testing it with 150 gph and 1 bubble per second of CO2 and it works perfectly - no gas accumulation for the last 6 hours.

The cost for the parts is only about $15 or less. The acrylic canister seems to have a very reliable seal - I've used 3 of them so far and none have leaked around the silicone gasket.

A future improvements (if I don't loose interest) a nipple on the canister lid for CO2 injection so the unsightly T would be gone.

--Nikolay
 

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Discussion Starter · #4 ·
The canister - any store that sells kitchen stuff or hobby supplies. Target, WalMart, anyone.

--Nikolay
 

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It may decrease the flow rate a lot

This is the best design I'v ever seen. FYI: as my estimation, due to its complexity, it may decrease the pump head at about 4 feet. Thus to install it inline, a more powerful pump may be needed. Also I would recommend to choose bigger fittings.
 

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Discussion Starter · #7 ·
After running the reactor for a week with 2 bubbles per second and a powerhead rated at 150 gph it accumulated about 75% gas in the canister and required bleeding to keep working.

The pH stabilized at 5.7 (@ KH=4) and never went lower than that. I don't know if the gas accumulation is due to saturation or just ineficiency. Also - the total water volume for the test was about 3 gallons with almost no surface agitaion. Maybe there was not enough CO2 escaping the water and allowing solubilization of more gas.

That is where I'm at in the moment. Seems far from say a 500 gph, super-duper, 100% solubilization, external reactor :-D

--Nikolay
 

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niko said:
The pH stabilized at 5.7 (@ KH=4) and never went lower than that. I don't know if the gas accumulation is due to saturation or just ineficiency.
--Nikolay
There has been much discussion on what the accumulated gas in reactors actually is. I'm not convinced that it is CO2. Tom Barr indicated that he is working on a venturi design for an external reactor, with the goal being to prevent the accumulation of excess gas. I've yet to here anything specific about his design. The accumulation of excess gas has been the problem that I've encountered with all external reactors, and I was hoping to hear that your design would prevent this. Maybe Tom will chime in to tell us about what he has planned to solve this.

Thanks for sharing your design Nikolay.
 

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Hi Niko, do you still use this reactor design, or have you modified it to address the gas bubble issue?

I am in dire need of a small external inline reactor like the one in your pictures so if it's working for you I will try it.
 

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Just a quick thought on the air in the top of the reactor.

Couple things that you could probably do to stop it:

1) increase the inlet tube size to allow more water in than out

2) flip side is to decrease the outlet tube size or increase resistance on the outlet side (ex spray bar)

3) install some sort of air vent to periodically bleed the air.

I use a dedicated powerhead with an inline reactor. 1/2 tubing to and from
I also crafted a spray bar which slows the water down on the output end.
Ever since I 've burped the reactor there has been water up to the check valve installed on the CO2 tubing.
 
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