Hi my heater in my 16 gal tank broke tonight it was 200 watt, the only spare I had was a 50 watt which I have put in the tank hoping it will do the trick until I can get one tomorrow please can anyone advise what make I should get as my heater was very old and as there are many brands on the market I am confused as what to buy I want a good brand that has a thermastat control.