drooping is generally caused by too much water

try adding another air stone

this helped enormously from my 2nd grow to my 3rd grow by adding a 3watt air pump

maybe the algae is covering the roots from getting oxygen

maybe try flushing a few times to get the algae off?

I use Hydroguard from Botanicare's line-up and I think it works better than when I used H202

good luck!