hsoil:... just stick it in and wait a bit for a reading,...
.... I'll still take the pH reading with a grain of salt, (not your fault, it's the drop test kits limitations), but if that's what the calculation is, it's within OK range,... What dosage did you use on the epsoms? ppm's aren't alarming on run-off, considering,.... and given that pH, and you having flushed recently (BTW, how much water did you put through?), I don't think this is a salt build up/pH lockout issue, likely still lack-of defc.'s, or damage from preflush conditions..? Not an easy diagnisis, with what we know so far,... that the little one is also suffering has me wondering,...but at least consistency is showing! --that can help,... feed well, and look into a PK booster, maybe mootch some off a friend, just to try? ...one last remote possibility, how old are the nute's, have they been exposed to hot/cold conditions, maybe gotten cross contaminated,... point being, sometimes the chemistry goes bad in the bottles!
I didn't run much water through just a light flush I only ran 3 gallons through when I should have ran 9 through it. With the Epsom salts I gave a dose of 2 tsp per gallon for both plants. I'll try to feed heavier and Maybee add some fox farm bloom nutes I have laying around or I'll just order a PK booster. Honestly I have wondered about the nutes being the problem the whole time so that could be a factor. I just got them around five months ago but there is no telling how long they sat there waiting to be shipped...for all I know they could be 2 years old lol I did have this problem when I was using fox farm nutes as well but that was because of ph the fox farm soil was like 4.5-5 on the runoff no matter what I did so I switched soil and nutrients. And the little one is showing right when the rest do around day 35-40. She's just very small because she's in a 1.5 gallon pot but the age is the same every time right when they go full on bloom it hits.... the Accurate 8 isn't that type of meter, it works on the same principle as the cheapie skinny soil pH probes you see at garden centers, etc.,.. it's just bigger and better built--> the long probe is the A 8 -->
-those dicks are shameless these days,.. so many fucked grows caused by their acidic, half cooked crap,...running on their past rep' for sure, but the pH issues have been around for 2 years now! Still, peep's keep coming back,... 
The nute's are probably fine, if your store has decent turn-over,.. bottles should have made-on dates too,.. extreme temps/big swings can screw with the solution stability in them, like any other product,... Are you saying you've not started bloom nutes yet? If so, small wonder about the P defc., but that's not part of the yellowing, I don't think,... more than one thing can be in play here, and that can muddy the diagnostic waters,.... and I'm no Muddy or JM, my mentors when they were here,... that it's hitting all the lants, at the same time/stage, is a big hint at what's happening,... try the nute' changes, and we'll see,.. reversal of symptoms likely won't happen, we're looking for a slowing or halt of progression,...
I have started bloom nutes I should have clarified my bad. I usually start bloom nutes a week after I see preflowers or see flowers start to form. I Just meant that I would try to add the Fox Farm as PK boosters on top of my General Organics bloom schedule. The tiger bloom seems to have a high P rating so I just meant to turn it up a notch I would add that along with the Bio bloom and bio bud. Ill try and see if that helps on the young one its most likely to late to notice a difference on the older one. Do plants use more sulfur during bloom? If so I can Maybee just start adding Epsom salts during the transition phase to stop that from even happening to begin with. The problem has never happened in veg. Or could it possibly just be that my well water has to much of something locking out another essential nutrient?
I appreciate you commenting on here I think that really is what it comes down to. I already harvested these two but I'm worried it will happen again. I have tried two different soils and two different nutrient lines and the same problem occurs with both. I even tried what waira recommended on the second plant and no change. It has to be the well water locking out nutrients. I'm glad you said that about the white deposits because I see that around the pots when I dump the old root ball and sometimes it's also around the roots themselves. I'm going to use bottled distilled water untill I get a filter. If that doesn't work I give up! LolI see Waira has ya well taken care of, just saw "well water" in your last post. I have some interesting experiences with this! My well water is very deep, down into the limestone, down into the second aquifer. So this water is older and has more calcium. My first plants had whacky problems on this raw well water, and when I checked the roots of one, they were physically caked with whice chuncky calcium type carbonate deposits like form around faucets!!! Yikes! The pH was high and PPM off the chart (prob all calcium lol), so I started using rainwater and filtering any well water I use through a Brita filter (it's not RO but it helps with PPM). No such probs since!
So it is possible that if your well water is really heavy and loaded, it could lock up and even physically lock out other nutes and cause some defs. It might be too late to really do a whole lot for your oldest girls there late in flower.
