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CO2 Reactors/Diffusers in large tanks

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Hey guys,

I was after some advice on the best way to inject CO2 into larger tanks.

I'm currently playing with a 300L tank and a normal ceramic diffuser has not been adequate. 

Im using a Sera reactor at the moment, which is attached to an external filter and a spray bar however the reactor may be faulty and not working quite right. So I'm keen to hear what experience others have had in getting good CO2 levels in their large tanks. 

Any tips on good reactors out there? Happy to hear about anyones DIY projects or commercial products, what ever has worked out best for you! ;) 

TIA 

 

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There are two widely used DIY reactor designs, the rex grigg and the cerges reactor

They'll both run around $50 to build, its generally accepted that the rex grigg design is better for maintaining flow while the cerges is easier to assemble

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I make my own from PVC pipe.  700 litre tank.  Bigger is not always better - the trick IMO is to have some turbulence where the water goes into the reactor to help dissolve the CO2. ie strong filter pump and don't make the inlet too big in diameter so the water squirts in.  e.g.  for my big tank I first used a 40cm length of 90mm pipe with end caps to make the reactor body with 3/4 (20mm) inlet and outlets and the water moved too slowly so would not dissolve all the CO2.  I chopped the top off the reactor and put in a 50mm->90mm reducer so the inlet of the reactor is narrower (ie the whole reactor is pear shaped) and I glued a small piece of 13mm pipe into the inlet hole to make a bit of a "jet".  So now the water squirts into the narrow top of the reactor with a lot of turbulence, but the larger bottom section slows the water down and traps any bubbles. Works well.

The DIY "cerges" using clear water filter chambers  are also great because you can see what is going on - but again good flow/turbulence is the key.

 

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I found with a 4ft tank that having a CO2 outlet at one end wasn’t enough. Pearling was only going on for two thirds of tank. Added CO2 outlet at other end and doing a lot better.

I’ve been happy with the CO2 probe cutoff as well. Much safer on fish but still managed to gas a few.

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Cheers for that, some good advice.

8 hours ago, Grubs said:

I chopped the top off the reactor and put in a 50mm->90mm reducer so the inlet of the reactor is narrower (ie the whole reactor is pear shaped) and I glued a small piece of 13mm pipe into the inlet hole to make a bit of a "jet".  So now the water squirts into the narrow top of the reactor with a lot of turbulence, but the larger bottom section slows the water down and traps any bubbles. Works well.

 

Thanks Grubs - Yeah the bigger tanks are more stable when running but can be a pain to set up. Your reactor sounds pretty good, what filter are you using to pump it? any pics of your the build? 

4 hours ago, Delapool said:

I found with a 4ft tank that having a CO2 outlet at one end wasn’t enough. Pearling was only going on for two thirds of tank. Added CO2 outlet at other end and doing a lot better.

I’ve been happy with the CO2 probe cutoff as well. Much safer on fish but still managed to gas a few.

 Good call, Ive noticed similar growth in my tank. It's pretty hard to get good mixing with just the one outlet

 

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