Gone missing

I am at a point where all opinions make me want to check twice. Even bad ideas are worth considering?
I've been going through all sorts of slow motion testing and trials to see why one plant refuses to work and in doing that I suddenly run into a totally unexpected problem.
I've had hard alkaline water in the Austin area for as long as I've had the tanks. PH of 7.8-8.0 is standard and with buffer of 250PPM and above, I had stopped testing all three as it was solid-- hard alkaline water.
But now it isn't??? Now it is coming in different.
Raw hard water-6.8
After softener-6.8
After setting in the reserve water barrel-6.4
120 gallon tank with PH controller set to 6.6
75 gallon CO2 injected-6.2
20 gallon injected-6.1
I think I see why growth in the 120 has ground to a stop!! I'm only getting .2 drop of PH when I thought I was getting a full 1.2!!

So when we have what sure looks like a deficiency of some sort, don't fall into the trap of KNOWING the PH or other parts are solid. Do the methodical testing to varify that is true.

DutchMuch

yep yep yep!