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This might come off as a rookie question, but I can't seem to figure it out. My question is about the corner overflows that have the little slots in them about halfway down When there is a power fail or return pump fail, wont these little slots allow the water to keep filling up the overflow...

I, know that a reef tank does not have the same water conditions as a standard horse tank. But aren't there horses that can take 80 degree water. The horse tank would be 30 gallons. and sparsely scaped. Also Ive heard of a product that can bring down a tanks temp 2-3 degrees. Put this on horse...