Some slightly encouraging news. This morning the PH had risen from 5.69 last night to 5.94 after 10 hours. Thats a big improvement from what it was doing. I can only assume that lowering the PH in the rez way down and/or flushing the system has helped in some way. I hope it used up or neutralized some of what ever is buffering the PH up so much.
I picked the best three clones and put them in to the totes. The one with the most/longest roots went into the NFT tote. The roots have the furthest to go to reach the water level in that tote. I put the one with the shortest roots into the E/F tote and the last one into the Membrane tote.
The new growth on all three is looking pretty good.
Im going to monitor the PH change closely for the next several days and if it doesnt settle down enough, I will start playing with my idea for a slow acid delivery system.
On another note, Ive decided to keep the rez temp around 66 deg F for now. The hope being to reduce risk of root issues with the lower temp.
I had been planning to run a sterile rez using pool shock - mainly for cost reasons and its simplicity.
BUT - then I read a scientific study on the use of chlorine, chloramine, H2O2, etc to treat and prevent root pathogens. According to that study, if you run high enough levels of chlorine, etc to actually kill the pathogens, it damages the roots and reduces growth. Running at levels that dont hurt the roots doesnt kill the bad stuff. Plus, active chlorine combines almost instantly with nitrogen in the nutes which reduces the availability of both in the system. Over all, that made it sound like a bad idea to go sterile with no up-side at all. Well, the one up-side would be if you went sterile from the beginning at moderate doses of chlorine, you might be able to prevent root pathogen growth from getting started - maybe - but at the cost of some damage to the roots.
Anyway, I decided to skip the chlorine and just keep temps down as long as possible. I will have some extra funds in a couple of weeks and will order some Hydroguard to use instead.