I think ya may be hitting on the money with CO2. I've looked at
cannisters, but the Carbo Plus is attracting my attention.

Not sure on po4, though.

Paul

Craig Brye wrote:

What are your PO4 and Nitrates at? I think your algae problems are due to
incorrect nutrient proportions coupled with a lot of light. I have almost
4
watts of light per gallon over my tank as well. One thing I've learned is
this much light requires a LOT of plants, a lot of fertilization of
correct proportions, and ample CO2 production.

--
Craig Brye
snip