What do you mean by hempy phenotypesgenetics? hempy phenotypes are pretty common from f2 breeders. or so i hear. but yeah, algae can't be good, cover the top of the medium with a black trashbag cut out for a while. should kill it.
The reason I ask is I'm using botanicare, but I have FF and GH nutes. I have read about people keeping pH from 5.7,5.8 then 6.2. Now I know that the standard hydro pH should be 5.8.I use the GH nutes, and absolutely love 'em. For veg I use an NPK of 5-5-10 and bloom 8-8-16.I try to keep my PH around 5.7-5.9 after letting the water sit to let out the chlorine and calm down to room temperature.
From what I can gather, a lot of that has to do with the water that comes out of your tap and if you let it sit. For some people, their water might come out PHed at 6, then they can simply pour some water, add nutes and be good to go. What I do is pour out a few gallons of water and let it sit for at least 24 hours to let all the chlorine and all that stuff out, at which point my tap water rises to anywhere from PH7 - PH8.5, which is due to all the acidic stuff coming out. I'll add more acid to get it down to where it needs to be before I add in the Nutes (I've found that adding nutes does nothing to lower or raise the PH in your water, BTW.)I have two in hempy right now, I use GH Maxi series. There are folks here that say you don't have to pH for hempy, I have not tried it. I just use the dropper kit and get it in the ball park and don't have any issues at all.