Before you make any purchases, you'll want to find out what your water ph is. An aquarium water ph test kit works ok. $6.00 or so. They're cheap, but fairly accurate. Best bet is a ph pen. I use a cheap Milwaukee ph pen, ($60.00 and up) but there's bunches of brands out there. Once you find out what adjustments are needed, General Hydroponics offers ph up, or ph down...likely you'll only need one of the two.