Does running a higher wattage heater for a shorter amount of time, or a smaller wattage heater for a longer time use less energy in the long run? For some reason I pulled my heater out today and realized it is only a 350watt on a 250gal system. I bought someones complete system, and thats what came with it. Tank temp maintains at about 80 with no issues, but I have a feeling that heater probably never shuts off at that wattage. Thoughts?