Ok so I have a 5 gallon glass tank now. I need a heater (b/c I returned the second heater I bought a couple days ago b/c I didn't like it since our house gets really cold at night and the water temp. was fluctuating too much and I couldn't tell if it was on or not) but I'm not sure which wattage of heater would be best for a 5 gallon tank. Some products say 25 watts is ideal for 2-5or8 gallons while others say 50 watts for 5-10gallons. I have no idea which would be better. I need a heater that I can set the temp on and know it's actually on or off. Thanks for all your input!