Random Thoughts

so Im having trouble maintaining the temperature at 79 in my 55 gallon with 20 g sump with about 15 g of water in it. Im running 1 150 watt in the return section and 1 100 watt heater in the 2.5 refugium. and 1 100 watt heater in the overflow section of my sump am I better off having one heater or 2? or is more the better? should i have one in the tank?

I completly redesigned my sump and replumbed my whole system will post pics when its completly finished

Thanks ...