I have a 90 gal tank and it's been pretty warm in NY state, however, I have been using tupperware bowls, filling with water and freezing them, then I remove the ice mold, put in plastic bag and float them. It seems to bring the temp down much better than ice cubes...they melt too fast. These blocks last a while an do the trick. Even with A/C going and room stable around 74, my tank will easily get up to 80+ and I want it down around 78, 79 tops. Also, I only have lights on for 2 hours early in morning and that's it. Someone told me the fish don't need all that light (hope that's true). Where is fall?????