I wouldn't, but you can.
I would test for chlorine. See how much if any is left in there.
Many aquarium stores sell dechlorinators. Would help.
Check PPM and ph... adjust as needed...
The algea is also bad....
I don't know man. I think it would be ok, but again, I personally wouldn't do it, and I do have a pool. Your call. I do dump lots of pool water directly onto a tree in my backyard. Haven't seen any bad side effects, and been doing this for a number of years now. Pool water is always splashing over the side onto nearby plants, and my lawn, again no bad side effects.
Guess that wasn't very decisive or helpful... I ramble a lot. Goodluck man, and happy growing.