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...
 

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guitarzan420

Well-Known Member
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.
 

Phenom420

Well-Known Member
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.
 
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