Dude, you are doing too much. You can not water them constantly, change this, change that etc. They sense your despair and will give you a reason for it. Man, that sound crazy, but many here will understand me lol.
Back to reality, the quality of this grow has gone to shit, they will not reach their potential, and what you get at the end is nowhere near what it could have been. Accept that, and see what you can salvage from here. At minimum you will get a great learning experience from this.
I'm fairly certain that your problems are not nutrient brand related, but rather lockout related due to low/ fluctuating ph. I'm hydro now, but I remember getting some Pro-mix batches that had that fucking low ph issue no matter what I did, God I hated that shit, constantly trying to fuck with the ph, hydrated lime, ph up you name, it I tried it. Meanwhile, your plants go too shit. You know what I did, I started to feed them my fucked up tab water (600ppm of God knows what plus chlorine lol), made sure I let them almost dry out between watering, and who would have thought, all my problems with my mother plants went away. Oh yeah, I also don't worry about the fucking ph anymore in my soil mothers, it is what it is.
I feed them when they lighten up a little, but other then that I just make sure I don't over water. Also, keep them in the shade while they are stressed, sick things don't like to be in the full sun
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Alright, now the soil guys can flame me ha!
Good luck bro!
Kind