I have the test kit already and I ordered some fill water from the same local pool fill company the owner uses. They will deliver today or Monday. Talking to a relative who has been a pool owner for 20 years, he has many opinions. One is this: he always adds fill water from his well without staining on his concrete pool, he said. Of course, we don't know what is or is not in his well water. My question is this: If my pool is 32k gallons, and I need to add 500 gallons to restore the proper level, what is the risk of metal staining assuming a normal well with some metals or minerals? Seems like a pretty low percentage of new water. And is there a way to treat or filter the new water to avoid staining? Buying water isn't very desirable.