I have the same issues but with Fox Farms. I have been running some experiments. I was using tap water that has sat out. My city does sometimes use chloramine. My bucket, normally wiht 1-1.5 gallons sits in my grow room. Temps stay below 80 at all times. I had an airstone in there as well to add O2 and keep stuff moving a bit... Water with nutes was going in at 6.5 and the next morning were up above 8.
I added a water pump to avoid any nutes settling. Seems to be working welll as it sucks from the very bottom of my bucket (which is used for my drip system).
I also started to use water that had been through my Pur faucet filter in my kitchen. It is supposed to remove chloramine.
Using that I mixed some water/nutes yesterday morning. They PHd at 5.5. I let them sit until late in the afternoon. They had definitely settled somewhat in that color at top and bottom of jug was different. PH had risen to 5.61. Given that my PH pen ain't perfect, I wil call that diff margin of error. I adjusted up to 5.95. I know too low but trying to compensate for expected rise that would come. Dumped in the bucket last night about 3 hrs before lights off. This morning just after lights on, PH was 6.7 so a significant rise but much less than when it was jumping up to 8. So the filtered water seemed to have helped.
I am convinced that the nutes are unstable but a certain amount of it is temp. I also read some way too technical for my brain on another forum that said PH will naturally change over the course of the day, up and down depnding on where you start, because stuff in the organic nutes change with lights, heat, etc just like the plant does. When the nutes go to sleep, PH changes so to speak. I'm not syaing it's accurate, just what I read from someone who sounded like a scientist to me.
For my next grow, I am going to get that bucket out of the grow room. I'm also moving to Dyna Grow as I've read good things about its stability.
