i agree with rzza ph is super important i would never use tap water without doing a ph test on it first. a test kit is like 5 bucks a garden or pool shop. and chances are you will never need ph up because tap water is usually really high in ph. usually ph up if for your hot tub because you cook...
your deffinately over watering man. i sometimes only water once a week and my plants love it. your plants will have an easier time trying to survive a little dry then flooding them