I had some bba not to long ago, I got rid of it by reducing photo period to 6 hours, overdosing excel, pruning the already affected leaves, upping co2 to over 30 ppm, and having some ottos in the tank helps as well because they will eat the dead bba but not while its alive. If none of that works try an algeacide such as tetra algae control it works well, another is api algaefix which I have heard it can work really well and it can also severely sicken and even kill fish so just be careful. hope this helps
Thanks for your info but this is a shrimp tank and the only thing I know I can use safely is excel. My problem is the BBA is all over substrate. As I said earlier, I really don't want to move the shrimp as there are 150+ in there. This really sucks because the water conditions were perfect, doing one 50% change a week ans water was crystal clear (which it still is). I don't understand why after using aged water for a couple water changes this crap appeared in all my tanks that I used it in. The others I got rid of it basically as you described above with lots of circulation. Has anyone else experienced this with aged water?? That's the million dollar question for me.