My 30G exploded with some kind of slimy string algae. NO3 is 0, so are phosphates. It happened within a day or 2 of replacing a 30W Vita-lite with a 30W Sylvania warm white bulb. That's the only thing different I can think of. I put the old Vita-lite back in & have been making 25% water changes every other day. It's still pretty bad. Any help would be appreciated. Tom Connors, Pittsburgh Pa.