Q: Differences between CO2 & Aeration

[Pinkey]

Hello,

I am looking to increase the CO2 in my tank for my plants but I lack the testing equipment to test for CO2 levels. I know some of you are experts and have possibly tried this.

Premise: A good CO2 system injects CO2 into the water so the water has a higher CO2 concentration than the atmosphere.

Premise: The atmosphere contains 387 ppmv CO2 or 0.0387% of the atmosphere is made of CO2.

Premise: A certain percentage of the gas in the water is made of CO2.

Question: Would increasing the amount of gas in the water through thorough aeration increase the amount of CO2 available to the plants? I am thinking of adding airlines before every impeller in the system and adding small pumps into the sump that would feed one another and create an innumerable amount of tiny bubbles increasing the air in the water and, theoretically, the amount if not the % of CO2. In short, could a heavily aerated system be as effective as a heavily injected system?

Have any of you tested this?

Thank you,
Pinkey

[rocker92]

i wouldnt think so, because there would still be the same mixture of co2 compared to air. in other words, there is more oxygen, so the likelyhood that the co2 levels would go up is minimal.


if you want more CO2 in your tank, you should go with a CO2 setup, this will make more CO2 avaible for the water to pick up.


good luck

[Star_Rider]

your system will help to keep CO2 in the tank water but would not come close to a pressurized CO2 system since it is adding far more CO2 to the water.
in essence most tanks with good gas exchange would be pretty good at replenishing the natural CO2 from the air..your fish are adding CO2 to the system when they respire.

but you would only be aiding to replace what is lost a little quicker.

Pressurized, injected CO2 is adding a much higher concentration of CO2 to the system.
remember the pressurized systems use reactors that mix the CO2 to existing tank water.

[dundadundun]

your sump would off gas co2 from a pressurized system for one so you won't get the full effect of a pressurized system without wasting a lot of co2. if you go pressurized it's best to get a decent canister filter.

if you have a low light system and just need to keep the co2 stable the air stones work well. if you're looking to go more the high light route and grow harder plants you're best off doing a canister and a pressurized co2 system.

all in all i'd have to agree with star_rider.

[excuzzzeme]

In a nutshell -


Aeration, the pumping of air into the water means CO2, Nitrogen, Oxygen, Hydrogen, and other misc. gases. These gases need contact time of X duration to be absorbed into the water column. The total amount you get is not sufficient to increase CO2 but because of it being mixed with other gases actually causes the water to off-gas it. It marginally increases the amount of Oxygen causing a decrease in the amount of usable CO2. The aeration also causes the light gases to off-gas as well

Perhaps an over-simplistic explanation, but close enough to give you an idea as to why CO2 is injected. HOB's/ wet/dry systems create more surface agitation than many canisters. That agitation of the surface water creates a larger surface area for the O2 to aid in the off-gassing of CO2. That is one of the reasons a canister is favored among planted tank aficionados.

I have many planted tanks and I use HOB's and no CO2 injection. I am not overly interested in having a show piece, rather have basic plants since they look better than plastic ones. I am sure they would benefit from the addition of CO2 though.

[jpappy789]

Without getting too far into chemistry and in a position to make a fool out of myself, basically the premise of injecting CO2 and subsequently minimizing the surface agitation is to get CO2 levels in the tank higher than they would be under natural conditions. Aeration will certainly increase the efficiency of CO2 dissolving into the water but it will not be able to reach the same level.