Yep, some fried tips.Hmm...I thought I could see some little fried tips there on the second pic. Plants that size shouldn't burn at 1ec, they should be able to handle 2ec without stressing.
Can't remember if it's P or K that causes the tips but its one of them.
What exactly are you feeding them?
Just checked but couldn't see it.
Using pk booster by any chance?
Here's the nutes I'm using: https://lotusnutrients.com/pages/easy-guide-and-recommended-hydroponic-feeding-schedule
Bloom and Boost are what I'm using right now.
So, a couple things:
* There are two different strains - both supposedly Indica-dominant, but one is definitely tall and lanky and the other short and stubby
* The shorter, bushier plants do NOT have nute burn; taller ones do
My interpretation was the shorter plants are hungrier and the taller ones get burnt way before the shorter ones do. Some of the lower leaves got burnt a few weeks back on the tall ones.
Right before the flip I was rocking along about 2.2 EC (feed schedule called for 2. and relatively stable pH when I noticed the tips on the taller plants got fried, so I backed it down to 2.0EC, - THIS IS ABOUT THE TIME I STARTED HAVING BIG PH DROPS (for whatever reason typing this out made me see that more clearly) but overnight it jumped to 2.9EC, so another res change and backed it down to 1.5EC - it was relatively stable for a couple days, EC dropped to 1.3 so I topped up with nute-water (probably should have just used plain water until the res change) to 1.6, then another pH crash to 4.6pH.
Res change to 1.5EC - next day was stable pH and 1.3EC, topped up with nute-water to 1.4EC; 12 hours later another pH crash to 4.7 and EC up to 1.6.
After that I've been walking down EC all the way to currently 0.6EC, which keeps the EC relatively stable and good water consumption, but pH drops into the 4s every 12 hours.
After reading what I typed, it almost seems like when I top up with nute-water I'm locking out at least some of the plants - which sort of makes sense, as I understand EC only indicates the level of TDS, not what KIND of TDS, so the plant may uptake X and Y, but have a lot of Z left in the res, then when I top up with nute-water I'm adding more of X and Y, but also more of Z - which could raise Z to lock-out levels, then somehow that makes the pH crash.
Wonder if I do a rinse with pH'd water for a few hours, then a res change with fresh nutes to like 1.0EC (and walk up from there to maybe 1.4 if it is stable), then only top-up with plain pH'd water between res changes would fix the issue...seems worth a shot.