The more I read about BBA, the more I'm getting lost. It seemed that BBA was a result of not enough Co2 or fluctuating levels of Co2, at least that's what I have read here many many times in this forum. But I cam across this info at http://www.gwapa.org/articles/algae/ and it states this about BBA : Black brush, or BBA, algae can be one of a number of specific genera of “red” algae in the Rhodophyta family. Most of the algae in this family are actually marine, but a few freshwater species exist that particularly target our planted aquariums. This algae may be black, brown, red, or green in coloration, and can quickly coat your plants and hardscape if not kept in check. Cause: Nutrient Imbalance - potentially excess N, P, Fe. Strive for the following nutrient levels: N (10-20ppm), P (0.5-2ppm), K (10-20ppm), Ca (10-30ppm), Mg (2-5ppm), Fe (.1ppm). Low pH - Neil Frank observes that African Rift tanks never have BBA. It’s believed that BBA thrives in acidic environments, which is unfortunately what most plants prefer. Cure: Increase CO2 - This will stimulate plant growth, which should help the plants out-compete the algae for resources. Excel/H202 treatment - Use a syringe to spot treat problem areas. Then manually remove when BBA turns grey/white. Manual removal - Use toothbrush to remove as much as possible. Bleach treatment - Dip affected hardscape items/hardy plants in a bleach/water solution using a 1:20 ratio of bleach to water. Before putting them back into the tank, make sure the item is free of bleach odor. OxiClean treatment - Dip affected hardscape items in a OxiClean solution, making sure you only use the original OxiClean with no other additives. Maintain proper water change/dosing schedule - weekly / bi-weekly changes. Algae Crew - Siamese Algae Eaters (SAE) and Amano shrimp are known to eat this algae. Copper (not recommended) - There are commercial algaecides containing copper that will kill BBA, but they will mostly likely also kill your plants. From the above, am I right to say that the advice to up the levels of Co2 in the tank is basically to boost the growth of plants so that they can overtake the algae in nutrient uptake? Its not the low Co2 but excess nutrients in the tank that actually promotes BBA? Anyone?