I as well have well water..sucks cause i got high ppm but its good water to drink :thumbsup: lol. Any way i need to use more ph down then i would if i had distilled water. i tried with both so i know for fact. i would end up under the 5.8 ph when trying to ph the distilled water. so i guess the more ppm the more ph solution your going to need. i use 15mL of ph down for 1 gallon of well water.