Are these Nutrient related problems?

I’m thinking I have several different plant problems here and I could sure use the help from you veteran growers. Especially from those of you with coco experience. I’m getting conflicting advice from all angles. Please help with this problem if you can.
All grown in 50/50 clean coco/perlite with temps 77° - 81° and humidity 50% - 60%. Lighting is under active air cooled 600W MH. Circulation fan with fresh air. Hand watered with RO. All nutes are ML per gallon: 16 ml CNS 17 Hydro Grow (3-2-4), 1 ml Cal Mg, 1 ml Rhizo, Ph’d down to 5.5 - 5.55 and around 940 ppm. Subsequent watering was followed with straight RO water (no other nutes or additives) ph’d to 5.55 for two days. Finally, I reduced the CNS 17 from 16 ml to 14 ml per gallon with same listed Cal Mg, Rhizo and watered yesterday. The problems listed below are on different plants. Some plants exhibit no problems what-so-ever while several others show the same symptoms.
LEAF Problem I - I began seeing small brown spots on the lower leaves. Believing initially it was perhaps a magnesium deficiency; I foliar sprayed Epsom salts ½ teaspoon to the quart, but have not noticed any significant changes over the past week. Then after some research, I began to think this might be a calcium problem.
Leaf Problem II - These have begun to appear on lower middle leaves (not bottom) as small, slightly shiny copper to bronze colored spots. I have no clue on what these might be.
Leaf Problem III - primarily on lower leaves working their way up. Similar to Leaf Problem I, but spots appear closer to the leaf edge.
Leaf Problem IV – I’m thinking this appears more like nute burn. Any input??
I’m more confused because I’m getting completely differentand conflicting answers as to my problems. Thanks to everyone for your help!!

I think it's a micro, I've seen this before and have only stopped it from growing worse. Last that I saw this was when a plant received a flush when it really just needed to absorb water. Ended up over watering it twice, since it needed food the next day to solve the flushing.

Alright... I know that many of you guys out there have experienced similar problems like this. Share your thoughts. I’m at a loss here.

I’ve reduced my nutrient strength by half. Additionally, I doubled the Cal Mg and the Rhizo to 2 ml per gal. each (ph’d down to 5.5).

I’m somewhat confident that I have nutrient burn, but remain unsure as to the other affected conditions. I want to take a better look at Potassium deficiency or lock-out as the case might be. I’m unsure as to the ph that potassium is best taken up, but should look into that. The necrosis appears to have subsided on a few plants but is slowly advancing on a few others.

C2L said:

Alright... I know that many of you guys out there have experienced similar problems like this. Share your thoughts. I’m at a loss here.

I’ve reduced my nutrient strength by half. Additionally, I doubled the Cal Mg and the Rhizo to 2 ml per gal. each (ph’d down to 5.5).

I’m somewhat confident that I have nutrient burn, but remain unsure as to the other affected conditions. I want to take a better look at Potassium deficiency or lock-out as the case might be. I’m unsure as to the ph that potassium is best taken up, but should look into that. The necrosis appears to have subsided on a few plants but is slowly advancing on a few others.

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I don't think I would worry about too much until I saw it replicate on newer fresher growth. Almost looks like a bit of burn from a previous foliar spray or from a slash of nutes on the leaves when you watered previously. More damage could be done by overreacting before it is determined as a problem or not.

Ph’d down to 5.5 - 5.55 and around 940 ppm. Subsequent watering was followed with straight RO water (no other nutes or additives) ph’d to 5.55 for two days.
...
LEAF Problem I - I began seeing small brown spots on the lower leaves.

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Yeah, no kidding?!

You can't run your pH in coco at 5.5 and not have this happen.

I can only assume that 16 ml per gallon of cns17 is sufficient since I don't use them to know the amounts. If it is, then your only problem here is pH.

Well not your only problem. After you fry them in acid, you starve them.

Give your normal nutes, well, depending on what the bottle says. I'm figuring that you don't give them full label direction strength, that's usually too much imo. But mainly get your pH between 5.8 and 6.2. never give plain water, always water with nutes and you should do it daily once your girl's back in good spirits. How's the rest of the plant look?