I am new to the hobby, and I have to ask a question about my heater. It is just a basic submersible heater from Petco for a 5-15 gallon tank. My tank is 14 gal. I never noticed this before but the light that shows it's on keeps going on and off. The outside sticky thermometer says the temp is around 79 but boy the water does not feel very warm to the touch. This is probably really stupid, cuz I can understand that the heater probably does cycle on and off according to the temp of the water, but just checking! *twirlysmi Thnks.