Big heater

[therapy]

I have a 375 gallon tank that is plumbed to my garage. The sump and a couple nemo dedicated tanks are in the garage all plumbed together. My tanks temp goes from about 80 degrees in the day down to 72 on these past cold nights. I have 3 250 watt heaters in the sump, but it dosent help to keep the temp very stable.
Do they make like a 800 watt heater or something like that? Will this 8-9 degree temp swing hurt my SPS corals in the long run?

 

[Aquafrags]

Get some 500 watters from Finnex, I run 2 on my 300 gallon system temp is right on

best thing to do if tank is in the garage, insulate the door, really made a diiference in the temp change in my garage