I read your original thread for details and go some, but would be easier for all if you gave a few tank parms, such as size, lighting, fert regimen, co2 or no, etc. Type of lights, duration, etc. This will get you better advice and replies.
BGA for me indicates low KN03 in my tank and for many others as well. Dirty filters and older substrates can also play a part............
Try increasing your kn03, and do bi-weekly 50% water changes for 2-3 weeks and perhaps reduce your lighting and see if that helps at all.
Hope this helps.