Thomas Love wrote, in part:
Therefore, for the maxim "add more CO2" to be the best advice>for an
algae
sufferer, I think these together are necessary and sufficient>conditions:
-
1. A well-planted tank;
2. The plants having good root systems.
3. With a fertile substrate.
4. Good lighting.
I suspect most people with algae will likely be failing on all>four
counts,
so adding CO2 will not help them.
CO2's effect on the pH and phosphorous adsorption may assist>but is
unlikely
to be sufficient alone.
I beg to differ from the above. The largest single material in plants, by
dry weight, is carbon. Carbon is not from the substrate, but for aquatic
plants from dissolved CO2 in the water. Depending on the definition of item
#4 on the list given above, that list could be a prescription for algae
regardless of the mineral content of the substrate if there is insufficient
bio-available carbon in the water.