I have a 5g and 10g tank. I had an older 100w heater that I put in the 10g and used the 50w heater that came with the 10g in the 5g. The 100w seems like it's being fritzy so I would like to buy a new heater. Question -- is a 100w heater too much for a 10g tank? I'm just not sure if I should buy a 25w for the 5 g and move the 50w back into the 10g, or just buy either another 50w or a 100w and be done with it. Where I am, a 50 watt heater is only about $1-2 less than 100watt. 25 watt heaters are MORE expensive than either. Bottom line -- I'm terrified of cooking my fish. Is there less chance of doing that with a lower watt heater, or does a stuck heater present the same danger no matter the wattage? Brands I'm considering after research are Eheim Jager (can I put this horizontally - that's the only way I think it will fit!) or Aqueon Pro. Thanks for any input!