ok, yeah man two waterings a day is wayyy too much. leave your plants alone for a couple days, the oxygen to your roots is necessary, even in hydro systems. Your tap water might not be too bad, mine is around 7.7, but drop it down to 6.5 so the plants have an easier time grabbing nutes from the soil... but yeah dude, i have smaller pots and i water it every 2 days at most. it wouldnt hurt to buy a ph meter and phup/down either, but your tapwater could be rockin.. read up about soil, plants, and ph'ed water, your babies will love you for it.