I think Rusty and WW can give you better advice then I, but I will just say that yeah before you throw pH down in there, be careful. The main point of my post was that when you have pure water at a 7.3-7.7 pH or whatever have you, adding nutes drops it considerably. I know you said you havent fed much, so that could mean pH isnt the issue, but its something to look at. So before you know what pH levels you are dealing with, I wouldnt use pH down, because it was my idea that the pH was already too low after adding nutes to the water... pH down would just make it worse...