I have a 1 gallon aquarium for my betta. Wal-Mart has a 7.5 watt heater, but it says it's for a 2-5 gallon tank. I know they say it's 5 watts per gallon, so I would like to know if this heater would be okay. I plan to upgade him to a 10 gallon tank as soon as money allows, so I could get a better suited heater. Currently he's on a heating pad, which is working, but I really don't like the idea of doing this much longer. Thanks in advance for any advice given.