wow, Im smart...u already stated u had problems with the digi meter. I think purified water gets purified via sodium chloride, i.e. salt. Im pretty sure that well water will be as hard as your tap water, or usually well water is very hard and/or contains too much of a mineral, i.e.-manganese, calcium, lime.
as for RIU, I have found that most members who reply are simply looking for an easy, 4 word sentence, to up both thier rep count and post counts. obvioulsy this matters more and is more important than helping those in need with the amount of effort to reply with depth and details if the original poster has provided enough info. check my posts-youll see many are paragraphs. than check someone like BuggBunny or Woomeister and u will see many 1 sentence posts. U make a good point on something that I unfortunately notice, but there are people here who generally want to help.
u obviously want some bangin heads for ur 'medical' condition, so here is what should do:
a-check the rockwool with your fingers pressing firmly into top right after watering and halfway in between waterings. the issue here has got to be root/rootzone, watering, nutrient uptakes, etc. rereading ur post, you said 2 mins 4 times a day. that does not seem like a lot. they look overwatered. but they are not. looks liuke reverse osmotic pressure.I would guess if you check the rockwool that you will find it drying out too quickly. I think the key word in your case is EC, or electrical conductivity, for the dissolved salts in the actual rockwool. There getting to be a bit more and more salt buildup on the coco pebbles-little white rings-I dont see them usually ever.
so, u r feeding minimially, with very high nute concentrations, using GH nutes-which are known to cause excessive salt buildup-this is got to be why your ph is getting slammed-
Like I stated in my previous post, I mean, if you were running 1000 ppm and your plants were 6 feet tall and in the middle of flowering, than maybe, just maybe, it would be possible to have such a high ph fluctuation from the plants uptaking the nutes-which are acidic-and resulting in the ph becoming more basic.
The nutes are concentrating more into the grow medium and staying there, while the water is passing through. And this I believe happens b/c the watering is too minimal. I know in soil this is a very large cause of issues and hydro in your set up is the same.
If you could buy some Clearex that would be ideal, and if not now, than in the future especially when going into flowering.
if you have RO machine than you can RO your hard tap water. for now, you are going to have to make up a concoction of very week nute solution, like 1/16 in 2 gallons, ph the water to 5.5 or so and run about a quart through each and every pot. wait 10 minutes and repeat. drain the res, refill with 5.7 -6.0 ph solution with maybe 1/4 of your Gh nute mix. by Saturday afternoon, they will not look anything like what you have now. most strain would have been totally fucked by now, but your friends want to grow. extend the drip times to 15 minutes at your current schedule.
couple more tips I have found on hydro
-superthrive-try using without
-drip method is fine but you may want to consider moving which ever ones u want to flower or until they show preflowers to their own 3 or 5 gallon pail with a simple DWC setup-bucket, pump, airstone-no timers, no nothing really other than checking ppm's and ph once a day. grow much faster and much healthier and giving at least 20 % more yields. fo sho.
here is a link that makes great toilet material n the basics of plant osmosis and nutes and symptoms, etx. is a long read
hit me back saturday eve and tell me they dont look like gold.
