Is a controller something seperate that will measure the temp and turn the heater on (sorry for what maya very newb question)? If so any recomendations on a model?
Yes the controller is a seperate unit that has a probe and a display screen.You can use two 75watt heaters instead of a 150watt remember to have a thermometer to make adjustments.Do not unplug in the summer months you might forget to plug it back in.Just a thought good luck.
Controllers can fail too i haven't heard of anyone cooking fish with a heaters in a long time not to say it doesn't happened .The more wattage the heater has,the quicker the water will reach the desired temprature.That means a 300 watt heater in a 75 gal tank the water would reach it's desired temprature faster than a 100 watt.The danger with that is if the 300 watt heater malfuntion it would be catastrophic for your animals, make sure you have a thermometer .
I think the new ones are fully submersible. Heaters are prone to failure even ebo j?ger which is why it's good to have two heaters instead of one big one on your system
Maybe some other users can chime in here with their experiences