Dear Allie:
Thank you for writing to me. A pool heater doesn't know if you have a 30 foot round above ground pool or a 30 foot in ground pool. The most important thing is that the heater is sized properly to the pool. Most all your heat is lost from water evaporating from the surface. So the surface square footage is used to calculate the right size heater. Make sure you have a licensed electrician wire it to make sure that it is safe. I hope that helps.
Sincerely,
Marcus
