I’m using tap water. I’m adding the ff trio nutes one and a time to a 5 gallon bucket of water stirring real good, let it sit for 20 minutes max, stir, adjust PH, stir and feed. I let it sit for an hour once, feed it and it locked my plant up. I only checked the PH right after I stirred the nutes in. I guess it could of been measured incorrectly, but highly unlikely. I only have had this problem once and the only thing I did different was let the mixed up nutrients sit in the solution forever and not check PH before feeding.