I have a 300 watt heater in my 55 gallon stocked with neons and bronze corys. I have it set at 74 but the read out always stays at 75 thus never turns on. My question is as follows. Can I take out the heater and not worry about it? Will the 55 stay at a more stable temperature than a 20 gallon? My 100 watt heater broke in my 20 gallon and the temperature fluctuates to the point that I think it's killing my shrimp. Thank you for your time.