I have two 150 watt heates one is the same one the OP has. I set mine to 89 and I get 80-81 out of mine. I factor in the fact I have an open canopy setup and more heat loss. In the summer it's always spot on only does this when the air is dense. This is in a basement btw.
No how will the fish breathe you will crash the nitrogen cycle. They make lids for tanks that have openings or you can diy. The more heat you trap the more the temps will be stable. Kind of like driving a car in the winter. It's warm inside but crack some of the Windows the temps will drop. Same concept here. That's why with lids you won't lose as much water with evaporation as well the condensation will build up on the lids. I
You aren't going to crash anything by covering the tank since you have a sump. If you are worried about aeration, but an airston in the sump.
Yeah the OP said should he cover the tank and sump. I said no and suggested a lid in his tank or a diy one.
Go get some eggcrate/light diffuser from HomeD and some thin acrylic. Cut the egg crate to fit the sump cutting out for hoses and wires ect...
Yeah I read that. And telling him he could crash his cycle is far fetched and a bit alarmist unless he silicones both tops down with an air tite seal....and even then...you gotta change the water sometime.
Thats an awesome DIY setup for a lid and I was just saying that it can crash it yes a little far fetched but I know some people who don't know too much about fish do some crazy stuff.
