Heat pump BTU recommendation for Nova Scotia, Canada

New pool owner and looking for recommendations from the experts on how many BTU's I need for my 21' AGP (10,400gal). Going to pick up a heat pump over the winter or spring but not sure if a 50k BTU will do or if i need a 100k BTU. looking to run the pool from May to September. Ill list the average temps below for my location and hopefully some in the same area or someone with the same average temps can chime in. The price difference between a 50k and 100k is about $1000 CAD. So if I can get away with a 50K BTU and save the $1000, that would be great. Thanks in advance for any help.

Average temps for each month:
May 54F ( Want to open pull mid May or so)
June 59F
July 65F
August 65F
September 58F (Close pool mid to late Sept)

First off, I don't know how to size a heat pump for a pool.. I'll presume you're in the ballpark with the 50K - 100K BTU heat pumps.
That said, I can offer you a couple things to consider:
Do you (plan to) use a solar cover / thermal blanket? These can greatly reduce thermal loss. Wall foam may also help but would require the pool be drained and the liner removed / re-installed.
Do you have time of day electric rates? If the smaller unit would have to run through the expensive parts of the day, if may be cheaper to operate the larger unit half the time when rates are less.
Be sure the heat pumps you are considering will operate effectively at the minimum teperatures you expect. Heat pumps have a minimum operating temperature below which they cannot take heat from the air. The minimum operating temperature is set by the heat pump's design and varies by manufacturer and model.

Good Luck and Welcome!

Hi and Welcome!

BD's got some good advice for you, Doug. Heat pumps are GREAT for pools in summer and for stretching into late spring and early fall, but they are not for fighter hard cold. What little I know is that the bigger you can afford, the less it needs to run to heat your pool.

Carl