Why no vacuum (just curious)?
Couldn't you use a leaf rake/net to scoop some of that organic debris out of the pool? Organic junk in the water increases chlorine consumption, although I don't know if it would use up as much as you are seeing (from FC 7 to FC 5 overnight).
Since you basically have no filtration at the moment, seems the best you can do, for now, is to remove larger stuff manually, keep the water moving, and watch chlorine levels closely. If your FC dropped from 7 to 5 overnight, it sounds like a SLAM may be in your future. I don't know if there are different rules for that with almost-new plaster...