yellow, crispy lower leaves - over fert or under??

okay... so I've grown a number of times, semi-successfully. . I recently moved cross-country (to a state with med mj, thank goodness), and now I'm having some new problems. In the past I think I was always way over ferting with chemical ferts, and getting my pH and salts way off - I'd have tons of yellowing by ~4 weeks into flower. so now I'm very wary of over ferting.


What I'm currently seeing is this:
four weeks ago I had 6 nice, 4 week old plants ~6" tall in 16oz cups. I had only ferted very lightly with much-diluted EJ grow, once. they were all nice and solid green, with healthy growth. I repotted them all into 1gal pots, in a mixture of potting soil and earthworm castings, and put under my 400W MH. They grew very nicely, happy for the new dirt.

10 days ago I noticed some necrosis on lower leaves and yellowing, so I flushed well (~2gal / pot), ferted w/ 1 tbsp / gal EJ Grow, and put on my 1kw HPS on 18/6. That's when the trouble really started...

6 days ago I noticed the necrosis and yellowing was much worse - the overall plants were now lime green, not a nice forest green like before. some lower leaves were very dry and crispy.

4 days ago things hadn't gotten any better, so I figured I had either salt buildup or a pH problem. I flushed the 1 gal pots AGAIN, very well - another ~2gal / pot.

today, I looked again and the problem has only gotten worse - all the plants are a yellow-green color (they look greener in the camera flash below than in real life), and all have significant numbers of dry, crispy fan leaves.


today I also bought a pH meter, which only has me more confused. I calibrated it with a 7.0 buffer soln, and got the following:
ph of buffer: 7.0
ph of tap water: 8.0
ph of runoff from pots at first water (w/ 8.0 pH input): ~6.5


so now I don't know what to do... questions for you all:

* It seems the pH of the tapwater I use is too high. do I need to use pH down before I water, or get RO water or something?? (TDS should be fine - I found the water quality report for my city online, and according to it I should have ~100ppm TDS)

* it looks like the runoff from the pot is in the normal range for soil, even with the high pH water in. does this mean my soil pH is okay?? I have some lime I could add, if this would help.

* have I over ferted or starved my poor gals??

thanks in advance.. I've read tons on here, but can't seem to figure out what's going on in my own grow...

looks like nute burn to me flush and use water only until they start recovering then i'd go only 1/4 strenght until they can take more. ph still high to start with 6.5 is your max really. good luck!

oh yeah, and:
* temps are ~70 at night, ~83 during the light phase.
* watering every 2-3 days, once plants are pretty good and dry

the soil runoff is sort of tea colored - definitely not clear, but not sludge or super dark either.

yeah nute burn most def
sorry man, that suck, but she will recover.

Welcome to RIU
use about 1/2 strength nutes after you flush, you should b fine.