The friendliest place on the web for anyone with an interest in aquariums or fish keeping!
If you have answers, please help by responding to the unanswered posts.
Most anywhere I have seen...3-5W per gallon is recommended. At 1W per 3g, that would be a 10W heater on a 30g tank. I would recommend 150W heater for a 30g tank
My tank is a 29 gal and i had one 200 watt heater in it and it seemed to overheat the tank.. Lowest setting wanted to take the tank to near 85f. I took that one back and got a 150 which seems to be doing awesome. You might also want to check the sides of the heater box as alot of heaters rate differently. It should give you a chart as to which of there wattage works best for the size. And i do agree that it is best to have 1 on hand just incase the others break as I know it the past Heaters really dont last forever.. Better to be safe than sorry...