Ok, I just finally read the end of this thread. I put my otos in earlier today, and they have been going at the brown algae on my tank glass like crazy. It's amazing how much clearer the glass is now. I can't wait to see what it looks like tomorrow.
So I couldn't wait any longer and I dropped a couple of algae wafers in. Geez, the poor otos and cories didn't get a chance! The platies and mollies were having a feeding frenzy on them, insane. The remaining fry in the tank had a little party--all of a sudden they came out of the plants and were swimming all over, I guess feeling safe since all the big fish were at the bottom fighting for the algae wafer.
Also, since I put the otos in, the other fish have seemed to discover the algae on the glass, and have been trying to eat that, too. It's very weird. I was worrying that the big male molly was going to damage his lips or something, the way he was banging at the glass to suck up the algae!