I wanted to buy a che yesterday for Phoenix so I can discard the purple night light but there were a few different wattages. What would be a suitable wattage for keeping a 75 gallon tank warm at night? Is there a formula for wattage per square foot or inch to go by or just a general rule of thumb that everyone follows?
How cold is the room the tank is in? I'd think the wattage needed would depend on that and on how warm you're trying to keep him. Keep in mind that they should have a chance to cool down some, unless you're in the process of fighting an illness. Also, will you be using a thermostat to control the temp?