Purple stems, over/underfeeding

I'm trying to get my feeding dialed in and keep having issues.

Plants are about two weeks into bloom, the stems were going a bit purple. I raised the bloom formula a bit, and the purple started going out of the stems, but now I'm getting burned tips AND yellowing leaves, at what I think are low nutrient levels.

Feeding Dynagrow grow/bloom at a bit under 1/2tsp per gallon. (It's actually 3 grams of each per 10 liters, converted to standard units)
Nothing else, I've discontinued floralicious plus and my silica supplement until I can figure this out.
Promix HP
I let it dry until the promix is 50-70% of it's saturated weight, then feed with about 15% runoff.
EC going in is 0.4 at most, pH coming out is around 5.6.

It seems like not enough food but every time I raise it I get burned tips and then later on more yellowing/spots. This is typical for me, but seems a bit worse since I went from coco to promix, and wasn't as bad when I was using botanicare PBP. And it's going to get worse.

I've included a picture of one of the lower leaves showing the start of the deficiency.

More about me: I've been growing off and on for almost 20 years and consistently grow the worst weed I've ever smoked. I make beer though, and it's almost always top notch, so I'm not totally hopeless.

May help, some led/quantum lights cause red/purple stems w/o having actual deficiencies

I'm not 100% sure if the red stems themselves are an issue. I've never had healthy plants and I'm always trying different things to sort them out, and I've been focused on the red stems lately. I boosted bloom a bit and they turned green again (just the stems, not the leaf stalks). But maybe they don't really matter.

The big issue is my impending leaves turning yellow, and later in flower falling off except for the top ones that look either dark purple or green that's so dark it's almost black. The leaves are already fading a bit but if I increase nutrients I get burned.

I have some plants further along in flower if anyone wants to see them, but it's an unsalvageable horror show. I posted my plants that are only two weeks into flower because this is where the problems start. They do mostly good in veg.

If your having issues with potential deficiency's late in flower, and the plants get burned with increased nutrients you may be dealing with lockout issues. Do you check your PH at all when watering?

becasueracecar09 said:

If your having issues with potential deficiency's late in flower, and the plants get burned with increased nutrients you may be dealing with lockout issues. Do you check your PH at all when watering?

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Right now it's going in about pH 6.0 and runoff is about 5.6. I used to pH my water to around 7.0 but it didn't seem to fix it, and runoff was still around 5.6.

teddy bonkers said:

using r/o or distilled water?

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No, but almost. My local water reports (when they published them online) were pretty uniformly low in everything. My Bluelabs Truncheon doesn't register anything in normal tap water.

teddy bonkers said:

I had same issues using r/o water, started using cal/mag and a little tap,(Mine is high in cal). and fixed it.

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Thanks! I'll try bumping one plant with a little calimagic, and see if that spruces it up. I've got a few plants, so I can try different fixes on different plants.