Hello I was told that it looked like red slime by a fish store .they sold me suff call (red slime remover ) I dosed the tank like the package said . It seamed like it did nothing . so they sold me another brand (chemiclean) , dosed tank per package . it has been two months now and its still there. make tank look bad . I have the water tested every week and do water 20% changes every other week. water tests good . i have chemi pure elite phosphate and silicate remover in sump .lighting is about 5 months old and run them about 7 hours aday .i have attached a pict . any ideas what it could be and how to get rid of it , so my tank will look nice and clear again . thanks