Reverse osmosis, is filtered water, Almost as clean as distilled. You will need some cal-mag plius to go back in the water. You need calcium and magnesium. You can get by with a little Epson salts for magnesium. That's a good price for a PH tester. IT just makes it easy to check twice a day. Just keep up the home work and ask questions. I could kill any house plaant on earth (with love). If I can do hydro anyone can.