Help me ID this algae... BGA?
Is this BGA? It's mostly on top of the water. It's dark and slimy, and generates millions of pretty big bubbles (no, the bubbles are not coming from the plants). It doesn't cling to plants tightly, it actually comes off very easily if the plants are disturbed, and then it floats around as small black strigy bits. I don't notice a strong smell. I've been trying to get rid of it for weeks, it keeps coming back. It started at the same time as a bout of green water. A UV sterilizer cleared up the green water, but this stuff has been tenacious. I have lots of light, lots of pressurized CO2, and have been dosing my usual ferts regime, with water changes (almost) weekly. I'm about to try erythromycin, so I want to make sure that it actually is bacteria. I swear, in my 11 years of experience with planted tanks, the one thing I've learned is that as soon as I'm done battling one type of algae, a new kind comes along. I can't believe that after so many years there are still new types of algae for me to discover!