BG algae in FW (maybe salt too but I haven't tried)

[Miss Jellybean]

First let me say that I HATE this stuff with a passion. In my bedroom I had a 10g tank with 1 small breeding pair of SA cichlids. Water always tested fine but I had BG algae covering the tank. At first the fry would nibble on it and it wasn't a problem. But then it just got out of hand. Everything was covered and something about it was negatively affecting the fish.

So I tried cleaning it ALL. Not a speck to be found, 90% water change, whole 9 yards. It came back.
So I tried cutting the light schedule, and repeating the above. It came back.
So I tried doing a black out and repeating the above. It came back
So I tried algae treatments and the above. It came back
So I decided I needed to understand my enemy better. I found information that this stuff acts as both an algae (feeding on nutrients and light) and a bacteria (creating it's own energy). It doesn't need, well, anything except water to survive. OMG! So I started asking around and bouncing ideas off other fish keepers and finally got the brilliant idea to try erythromycin. Hey, the algae treatment didn't work, maybe the antibiotic would? At this point I was ready to tear the tank down and give up.
So I repeated the first step AGAIN, dosed with erythromycin, and did a 3 day blackout followed by reduced light for 2 more days. Guess what? After 5 days of antibiotics it was all dead!!!!!! It NEVER came back.... until I moved that tank and put a 20g there.... Now the 20g has a problem. I'm waiting for fry to grow a bit more before I treat. I have 6 other tanks in the house and *knock on wood* have never seen BGA in any except in that one location. Weird right?

After 2 years of fighting with this mess I had the cure all along in my emergency kit. Oh well, I hope this adventure can save someone else the frustration.

BTW I have no reason to believe it wouldn't work in a SW tank but I have never had one and know too little about it. For all I know erythromycin is poison to coral... If someone tries/tried this in SW would you let me know? I'm a curious little cat