Planted Tank Guru
Join Date: Jun 2004
Location: Baton Rouge, LA
How about too little light? PC bulbs only last about a year before spectrum and intensity degrades. And you've been running that tank just over a year now. How old is the bulb?
Don't discount the effect of the BBA itself. Once widespread, it creates its own conditions for continued growth, by affecting the health of plants. Trimming, spot treatments, and correction of other initial issues may not easily break the cycle. If you don't have any Excel-sensitive species, try a full tank overdose.
Finally, boil that driftwood. BBA sinks roots deep in it, which H2O2 doesn't effectively reach; so it'll continue to be a harbor for BBA to pop right back out and spread.