Anyone have any pool heater info they wanna share with me?

Wifey has been lobbying for a heater and is armed with her mother's
chequebook. In the interest of staying married I've caved in and
decided that a heater might be a good thing for our kids... I just
agreed to this 15 minutes ago, so haven't Googled anything yet.

Pool dimensions are 16 x 32 x 10 feet deep (3 feet at shallow end).

Ontario Canada. Typically our water is heated by the sun to 23 or 24,
which I think is 76F. In hot days it can get to 80F. Want a heater
that will give us 29 to 30 which I think is 85F but if not, at least to
maintain 80F.

Natural gas. Chlorine, Sand filter.

One other question, are these things power vent or pvc exhaust or are
they stack exhaust? Want to keep indoors but wonder about air breathing.