this is a prob,in hydro you want ur PH to be in the range of 5.5 to 6.5, PH is a big part of growing. the plant may not be able to use the lil bit of nutes that are in the water, also if useing tap water i whould get some CAL/MAG for later.. water: RO or tap has lil in them...IMO if i was in ur...