Can I use a 150 watt (40 gal) heater in a 20 gallon aquarium?

The heater will work. However if the thermostat sticks as they sometimes do, there will be enough energy to bake your little buddies. The best scenario is to use two smaller wattage heaters. Check out the shortcut I have attached.

Good luck

No. I have been given a 28 gallon for $80 4 (and it blanketed lights), and then an extremely large bio pump made for fifty gallons for $30something, and that remains under this 20 gallon. each so often the contraptions fee greater beneficial than in case you purchase each thing separate. I even have goldfish, nonetheless, so I havent bought a heater, however the different stuff -- nutrients, conditioner, is low fee, and the heater could could desire to be costly to make this sound precious to me -- except evidently marvelous or something. Mine is somewhat greater costly than the rectangle aquariums considering it incredibly is a bow front. I have been given all this from PetsMart. in case you get the common rectangle 28-30 gallon, it incredibly is $seventy two or something, and a 20 gallon there with lid and lightweight is $fifty 4, after which you purchase the clear out and different stuff.

You could try to put it into the aquarium on its lowest setting and monitor the temperature. Take it out if you think the heater is raising the temperature too much, and go out and buy a 20g heater. Without the specific brand of heater you have, it's hard to tell whether or not it will be okay.

I really wouldn't take the chance a smaller one would probably be less expensive;)