> The coco's been stable, pH wise, but maybe with age now, it's changing.
Nah, that doesn't make sense. It's just cellulose fiber (plus people use it over an over). It has to be something else.
> This is what I bought, and I did rinse it in about 30 gallons before use, it says it comes double rinsed already:
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
I have bought brick coco off Amazon a couple of times now. Both times it said ultra pure, triple washed etc etc, but when I put my PPM meter in it said otherwise. From now on I'm ponying up the $$ for name brand (GH!) washed, bagged, pre-Ca-treated coco. Spending hours washing the crap out of cheap coco is for da boids.
> I'll try upping the N a little. GWE says that N is detrimental in flower stage, but what the heck, it's worth a try. I'll bump up the Micro. What puzzles me is that I've got contradicting signs: lower leaves are yellowing and dying, yet I have yellow tips that indicate nute burn. I can't have too little and too much N at the same time. That's what makes me think this is a pH imbalance in the roots.
You can damage the tips with just one overfeeding that's used up by the plant or washed away by a flush or diluted by added water. My point is a toxic concentration and come and go in a matter of days.
> I forgot to mention that I started mixing molasses into the nutes about a week ago and that's about when the root pH starting going way high, but I'm not convinced it was the cause. I've since stopped adding it, but root pH is still way higher than I'm putting in.
I've tried molasses a couple of times and think it's better to put it on your oatmeal, but I don't think it does any harm, either. It won't affect pH.
I have to stay with my first guess that like so many of us, in flower you just got the N too low. It happens all the time.
Again, if you just water once a day (or 2X daily in my case) with diluted nutes--say 50% of Nebula's chart--you should't have any problems. (But as OzBud says, keep the Ca/Mg at 100%.)
<edit> I looked at your photos again. It's so hard to do diagnosis from photos, but you know what I'm starting to think now? Maybe (just maybe) magnesium deficiency:
http://www.growweedeasy.com/magnesium-deficiency-cannabis When I skipped adding CaliMagic one time earlier in this grow (I was just topping off the reservoir and thought I could coast on last weeks dose), I got classic Mg deficiency symptoms of interveinal chlorosis. Mine looked more like Nebula's photos than yours, with greenish veins and yellowing in between, but your leaves look like they could be just more advanced. And as my doctor says, there's no reason that just because you have cancer you can't have a heart attack, which it to say it could very well be BOTH N and Mg deficiency--they're both very common.
In any case, bottom line, do make sure the 1) you're feeding enough, 2) your feeding regularly (daily is my preferred), and you're giving any coco grow plenty of CaMg, especially if you live somewhere with soft water).
And finally, you're in the home stretch and your flowers look good, so you're doing something right!
