Hi. I'm looking to get some backup power recommendations for my two reef tanks. It would need to run two skimmers, 4 powerheads, and the lighting for both tanks. I've seen 1000watt and 2000 watt units. The 1000 watt seems to fit my need. However, how long would it power the equipment in terms of hours. Also if anyone can steer me to a good brand would be appreciated. TIA