Help my BTA is dying

[mike31154]

My guess would be lack of light. I didn't find a lot of info on Fluval m48 in a search, but a for sale listing showed the specs & if you only have one of these over a 90 gallon, I'm pretty sure it's insufficient. From the info I got online it's only a 46 watt fixture. The photos look like the LEDs are low power SMD 5050 strip lights which might be fine for a FOWLR or tank with soft/low light coral, but won't cut it long term with anything else. Maybe if you had about 4 of these over the tank, very close to the water surface, the BTA would settle down.

What size was your previous tank & what type/power of lighting did you have over it?