My tank is 78 at night and 80 81 during the day is this ok

Good morning! I had a hope to be a simple question for maintaining stable tank temp. I have been cycling my reef tank for a week, and notice especially with lights on, tank runs hot. Hard to keep at 78 or below without floating frozen bottle of water. My tank is small, 29 gallon and its been HOT...

Hey I am suspending my 130 watt ESU coralife hood above my 20 gal Long. I am wondering how high above the water can I go before the usable light levels decrease dramatically? I was thinking 4 inches above the water. It makes the tank look great and 4 inches seems just right. Oh and what is the...