Excessive algae is a symptom ...

Excessive algae is a symptom of imbalance in the lake's eco-system; typically low D.O. levels. When we treat a symptom, it tends to relieve the visible problem and if that's your goal then that's great. Unfortunately, dead algae cells precipitate to the benthic zone where vertebrates and invertebrates can feed on them. Unfortunately, nature's clean-up organisms (aerobic bacteria) also begin to metabolise the biomass but to do this, they need lost of D.O. As a result of this demand, the D.O. is stripped from the lake and anaerobic bacteria take over resulting in their noxious by-products.

Killing the algae does not get to the root cause which is low D.O. levels in the water.