Note this is a pretty ghetto setup as I was tired of waiting for the hydro kit for the S21 Pro to come out so I decided to try with air based on an old experiment I saw by someone else where they did similar to heat a bathtub using a S9. Lots of heat will be lost thanks to the ducting but hopefully at least 20% is going into the pool. Cost is $40 canadian for the ducting plus probably $10 I used in duct tape and 3d print filament. Sorry I can't figure out how to get pics to show up on the forum.
https://imgur.com/a/4B86nAOCurrently pool is at 24 celsius so will see how things look later.