My take on BBA is that organics cause it. The tank is dirty although it may look clear as a mountain stream. Maybe I missed it but in 4 pages of posts there was only one mentioning of the filter (A Fluval 406 on this 60 gallon tank). No note what is in the filter.
Two experiences about successfuly getting rid of BBA.
Tank 1 - made me think organics cause BBA.
Tank 2 - made me think good plant growth stops BBA.
160 gallon tank.
About 50 3" fish (Black Halfbeaks, wild).
2 large size Eheims (4 gallon volume each) but full of crappy biomedia that never looked well colonized.
No mechanical filtration.
One day - an explosion of BBA. Found a few dead fish. Removed fish, changed 30% water every other day for 10 days. Added mechanical filtration. BBA went away completely. Removed mechanical filter.
After a few days - a new BBA explosion. Found dead fish again. Turns out fish were getting territorial with age. When I didn't feed them they got really nasty with each other to the point of killing. Changed water again - 30% every other day. Ran mechanical filter again. Fed fish well but never let food linger in the water or fall to the bottom. BBA went away after about 5 such water changes.
Played this game 3 or 4 more times until all but 1 fish was left in the tank. Every time the water changes got rid of the BBA. The mechanical filter must have only helped.
Got the notion that decaying matter causes BBA. And the remainings of that matter maybe minor but they support the BBA once it appears.
65 gallon tank.
Prunning 1 to 2 handfuls every week for years.
Negligible amount of BBA + Clado for years. Up and down but never taking over in a too noticeable way.
Some of the BBA was forever on top of the sponge of the CO2 reactor (where the CO2 microbubbles come out).
Filter is ridiculous - AquaClear. No mechanical filtration. Volume of biomedia is about a pint and a half. Ridiculous. Part of the problem. Or so I thought.
Got sick of constantly present BBA + Clado and never really figuring out how to make to deal with them. Excel never helped, just slightly reduced Clado growth and killed Valisnerias. Embarked on a war:
Vacuumed bottom for a few weeks to remove organics. Bottom stayed clean after that. BBA + Clado still there.
Reduced N and P. Plants slowed growth. Clado gone. BBA - same.
Ran out of CSM - got Fluorish this time. Plants started growing very well despite lower N and P. Figured out old Trace mix was too old. Tank looks like new now, a month later. BBA gone. Discus spawned first time ever.
Introduced new, heavy BBA with some Anubias - within 2 weeks that BBA is now just tiny dots, going away too.
Got the notion organics are not the only culprit. Good plant growth does something to BBA.
1. Clean your tank very well.
Filter must have good mechanical AND biological filtration. Good amount of biomedia (Aim for 10% of tank volume. Yes 10%. More if possible.). Good flow through the media at all times.
2. Make sure the plants grow well.
Not sure how that works in a non-CO2 tank especially if BBA is already looking like it looks on the pictures on page 1.
3. Animal that eats BBA for sure - Styphodon ornatus. A goby that can completely clear a 3 sq. inches of BBA in 2-3 days and not harm even fine new Java Moss leaves. Problem with it - it likes to clean one single area and nothing else.