All my water parameters are perfect.My tank is 18 mouths old.I am still losing fish too ick.My corals are doing great, but in the night my tank temp still drops too low.I think a drop of 3 degress or less is ok.I have a good heater in the sump I have made several adjust too try to keep the temp at the 3 degrees or less line, but the temp still seems to drop 4-6 degress on me in the night .I think the 4-6 degress is to low and I think this is my problem .Is there any ideas on how to control my temp,or do I need to buy a better heater or do I need 2 heaters .The one I run now is a Visa-therm 300w.Is this too small for my 75g? Do I need to put a heater in the tank and the sump?The sump is 20g for a total of about 90g.Any help would be nice so I can enjoy my fish and stop buring them.