Christening the Algae Board

[kuhli]

I'm wondering if people who've installed pressurized CO2 systems have seen a reduction in algae. I've read the Sears-Conlin paper that basically suggests that increased CO2 will increase the competitive strength of the plants vs the everpresent algae. Can anyone verify this in practice?

[m.lemay]

Well its not that simple. Firstly you need a lot of plants. Secondly you need a lot of light , 2.5-3 watts per gallon. With that amount of light the plants consume nutrients from the water column reducing nitrates phosphates and trace nutrients. By introducing high lighting to the equation , CO2 consumption becomes the limiting factor to your plants thereby limiting thier ability to uptake the other nutrients from the water column. By introducing CO2 ( a macro nutrient), the plants really take off and consume nitrates and phosphates ( major algae requirements) and therfore outcompete the algae for nutrients. I've never had an algae outbreak in my 75 gal ,heavily planted ,well lit, co2 supplemented tank. The only algae that ever appears in that tank is green spot algae on the glass itself. As a matter of fact, my plants consume so much nitrates that my nitrates go down to zero. I have to add nitrates to the tank via plant sticks in the substrate.

[Steve Hampton]

Some algaes will be reduced by adding a consistant stable supply of CO2, some will remain uneffected. In most cases BBA can be eliminated with CO2 injection. In fact, I've never had BBA in a tank with pressurized CO2.