Cool project, and thats an awesome pool there boss - my personal fav a dedicated shallow and deep area.
I should never do math while sitting home sick a 1.5 HP pump is actually 1119 watts- still a lot.
With poolguy NJ's directional advice and a 24/7 pump run you may find that to be enough- if not i think you are spot on about the 1.5 HP pump.
The stuff that gathers on the top because of poor circulation will whack your free chlorine for sure and getting the top clean will improve your ability to hold the chlorine.
I myself would get a jandy epump 1.5 hp version to do this. I like the pentair pump a bit better, with the exception of the pump pot size, but they are all wickedly powerful and if you have any kind of a logic issue or somehow the pump gets up to full speed without a throttle the full 3 HP could be dangerous to your plumbing. You can run it at full speed during the day and cut it back to 1 HP or less at night.
The epump has the same rare earth magnet tech and will give you cost efficient run times and with a 1.5 HP max even if the pump somehow defaults to full speed you wont risk bursting anything.
(curious - is there a 2 speed pump with 1.5 max and rare earth tech? if so that would be enough rather than a full variable setup)
I think your chlorination "problem" would be ameliorated with better circulation.
Im really surprised you can run any kind of pressure cleaner off a return line in this setup- I wouldnt think it has enough oomph unless you block the other eyes and even then....
As much as I hesitate to ever add "more pump" I think you have this nailed.
Uncle Dave
I'm really liking your ride though; that is sweet 
