I had the same problem with the 13w light on the spec being too much without co2, experiencing algae everywhere (especially on the glass). After I added 1 nerite snail, though, the tank seems to be in balance. A while ago, I took the snail out so I could treat for hydra, and the tank crashed again. After adding the nerite back in, it bounced right back. I'd love to hear if you find another solution, though!