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Re: CO2 Generator
> My question is will this be adequate to diffuse the CO2 into the tank?
If no visible CO2 bubbles make it to the surface, the CO2 has completely diffused into the
water. Some folks use "reactors" to lengthen the residence time of the gas in contact with
the water and improve uptake. In plain words, the bubbles don't make it to the surface.
A lot of atention is paid to the amount of CO2 being added but consier that CO2 is quickly
lost at the water/air interface if the water is agitated. The effect is similar to shaking a
bottle of carbonated soda - the CO2 moves temporarliy away from equilibrium and out of
solution . Biowheels and powerheads (airstones?) which agitate the surface of the water
increase the rate of CO2 diffusing out of the tank (good for fish, maybe not so good for
plants). Users of cartridge CO2 can simply increase the addition rate to compensate, but DIY
CO2 rigs are usually capacity limited. I suspect that some of the mixed results with DIY CO2
injection may be due to the amount of surface agitation present.
I add my CO2 to the discharge of my power head via the hole in the top of the exit tube (a CO2
"eductor"). The CO2 bubbles mix quickly with the water jet and no bubbles persist. I dont
create too much surface turbulence since my power head outlet is 12 inches below the surface
and points slightly downward. In the past, I didnt care for the rapid current in the tank
and I made a diffuser out of PVC (1/2 inch swaging to 2" with 32 - 1/4" drill holes) which I
routed behind some rocks. This type of rig could be considered.
Intersting point about disolved gases - does raising the oxygen content of the water via
airstones or surface agitation reduce the amount of available iron nutrient (i.e does it
oxidize iron from the useful ferrous form to the ineffective ferric form?)