[CeceliaJ]

I know I want an Aqueon Pro but I'm not sure if I should get 150w or 200w.

My tank is 37g (probably more like 38 accounting for extra water flowing thru canister filter). Ambient temp of the room its in is 68-70 degrees, maybe a little warmer in summer. I want to keep the tank between 80-82.

 

[PlantedRich]

I would go with the 150 in that case. There is no sure way to predict what each tank will need due to the different ways we all have them set. Covers will hold different amounts of heat in. Different filters and their location will add varied amounts of heat. A filter that uses lots of power and is placed under the tank will let lots of heat go up into the water while a HOB drawing far less power won't heat the tank as much. Lights can be super hot or somewhat cool.
A smaller hearer will give you more chance to catch the problem if it sticks on that a larger heater might.
Hot tank= low O2= DEAD fish

 

[bsherwood]

I hate heaters- with 10 tanks it seems i am replacing heaters on a monthly basis. I recently bought 3- 300watt Eheim's as someone said they are durable and will last for 10-15 years. We shall see