Just throwing it out there, when I had a 55 gallon with a screen top I had 0 problem with keeping up humidity when using EcoEarth. I have had more problems with humidity with my T8. I bought it with light holes in the top because I was using heat lamps. When I switched to the under heater I still have humidity issues. I had to cover the top holes to help trap it in. I am planning on buying a solid top for it over the holidays.