We've been adding flourish since we set the tank up, and it actually grew while we were doing so. The bba we've encountered in the past has been course and wirey and is easily removed from plants and wood. This is velvety and strong, we have to scrape at it with a knife to remove, if you try and pull it off it's roots remain, it is only on the wood and not on the plants. Personally we're not too worried about it, it adds character to the tank and adds that natural look we've worked hard to achieve, we just wanted to know if it was harmful to the fish.
Cheers Chris b and Shell, this is our 6th try and we're finally getting the look we've wanted.
Thanks for the welcome back Snookie, but we won't be hanging round much as this place makes us feel about as welcome as a fart in a space suit....