I used to have a huge collection of healthy GBTA in my 90 gal tank but high nitrate levels because of my huge fish load, I put in a well lit HOB fuge (96W 6700k CF lit 18hours) filled with Cheato and the nitrate levels went to very low, but the GBTA started to turn white and over the last 5 months have shrunk to tiny lumps. now my xenia and RBTA are also shrinking and going away. I am thinking that the cheato is out competing with the photosynthetic apparatus of these guys. I am pretty sure it is not buildup of something bad because I can do huge water changes and they dont come back. Any advice? Should I pull the plug on the fuge, decrease the hours ( I already cut back to 12 hours) it is lit or try supplementing with something? If so what?