I had the same decision to make this year between the 75 and 90. Was concerned about the lights on the 90 over the 75. I was using VHOs on my 45gal. When I upgraded I switched some of the VHOs to T5HOs with SLRs (Single Lamp Reflector). I don't think you will have a problem with the 90. I purchased the 90 for the extra capacity and am very happy with it.