Wondering if anyone's played around with a recirculating CO2 reactor design, similar to reef tank calcium reactors. The idea is to use a small pump to recirculate water through a reactor chamber. CO2 and new tank water are introduced on the intake side of the pump. CO2-laden water exits somewhere along the way, often at the top of the reactor chamber. See the many commercial calcium reactor offerings for examples. Bio-balls or some other inert media would replace the aragonite in the planted-tank version. Seems like we could get good CO2 saturation, just not sure about matching the size of the pump to the rate at which new water is introduced into the circuit, or, for that matter, if it would be worth the effort at all.

I believe that the nature of CO2 is such that it disolves very quickly in water with minor agitation. Several scientific studies have demonstarted this. In fact, even the bioballs you see in many reactors are not needed.

Therefore, re-circulation would not saturate the water with any more CO2 than a simple reactor would.

Nick

Overkill then. Thanks Nicholas.

CO2 will dissolve much easier than O2 in water.
That's why the O2 build up during the day in the reactors(O2 saturation goes up).

The CO2 can still dissolve, but there's a lot of O2 in the way so that reduces flow and efficiency somewhat.

I added the venturi to waste this O2 if the level built up to a pre set level in the DIY CO2 reactor design.

So once the O2 gets down say 2", then the venturi kicks in and mist out the O2 and allowsw the CO2 to be dissolved well.

The mist that comes out is O2 and CO2 and the CO2 gets dissolved and the O2 is often released to the air above.

If you watch your reactor eariler when the light first come on, the level in the tube before the lights come on is very large from last night(if you shut the CO2 reactor pump off at night).

When the flow begins, this bubble reduces rapidly, unlike at night right before the lights go out.

Why? Why doesn't the bubble dissolve so fast in the evening? High CO2?
No way.

High O2? Yes, the O2 is highest about the time the lights go off and well over 100% saturation in most tanks. Come morning, the O2 is below 100, often 75-90%, then the O2 dissolves very rapidly and is gone inside a few minutes.

The degassing that occurs in the reactor tubes and canister filters is O2, not CO2.

The CO2 and the DO can be critically measuired over a 24 hour peroid and you'll see the plot clearly.

I'll see if I can put a grpah up on this site.
Never done that before but it shoudl help.

Kalk reactors are designed to dissolve CaCO3, not inject CO2 into water and degas O2 out of the tube.

Different purpose and they cost more and more PITA to design, as said, overkill, they want each bit of CO2 to roast the CaCO3 since the Ca++ and the CO3-- are what they want. So for 600-700$ you can set one up:-)
Or DIY and be able to have the skills needed. I made 3 of them.

Regards,
Tom Barr

tom, i know this has been discussed many times before. in this age of super measuring devices,wouldn't be it be nice for someone to come up with a (affordible) way to now how much co2,say at mid afternoon,you are injecting into tank. i'm burned on test kits,not reliable.not even pricey ones. allmost killing your livestock,i've found is too risky. there's gotta be a better way! 100$ would not be too much for a very reliable testing device when you have many tanks. regards,cornhusker