Aero guys use sub pumps all the time. If you are worried about it, stick it in the tub and flush with some bleach or clearex (or the like), then flush with water.
http://www.growweedeasy.com/marijuana-symptoms
Given that leaf turning down, I'd guess
Signs of Nitrogen Toxicity
Dark green leaves and foliage
Leaf tips may turn down, without signs of overwatering.
You may notice yellowing on the affected leaves or other signs of nutrient deficiencies as...
ok, I think I figured out what they didn't like. Right around this time I started shaking my nutes before mixing things up. Why? Cause I was reading the back of one for some reason and it said to. Fast forward to the next round and I was having the same problem during veg then it hit me...
Ok, but what are you using for a level switch? What I'd like is when the smaller res inside gets to a certain level, it turns on the pump to the outside res.
I'm trying to find a pump I can use to pump from a reservoir inside my tent to one outside. Temps inside are way to high so I want to drain to one res and when the level gets to a point, pump to one outside. Basically a sump pump but would rather have something smaller than what I'm finding...
Well, I was talking a few hrs not a couple days or something that my PH dropped. That said, these leaves are still turning and my PH has been fine for a week.
Right now my rez is a 120qt cooler that I have outside my tent but I just bought a bigger one (150qt). I did things so my rez wasnt' inside the tent. Make cleaning/adding water & nutes much easier. Also have a chiller hooked up to it