Black spotting on leaves - Nitrogen burn?

I fed my plants at 100% of fox farm soil schedule on Day 35 and Day 43.
5.8 ph, 1,800 EC going in.
The runoff was 4,000 EC and 6.6ph for the plant with black spotting leaves.
The “healthier” plant had a runoff of 3,800 EC, 6.6ph (see left plant below).


The plant on the right has the leaves with black spotting which I mostly pruned off before taking the photo, (see below):

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I stay at 1/4 fox farms recommended feeding schedule so far as it’s what I’ve heard recommended the most

I’m using fox farms happy frog 100% for soil. I’d wait for more experienced growers to reply as it’s my first grow but I’d say you’d want to do a good PH’d water watering and get a fair amount of runoff during next watering and retest before feeding neuts again. I usually try to get at least 1/4 gallon of runoff out of 1.5 gallons per plant (I’m using 5 gallon fabric pots and only water once pots are nearly weightless but before I see any droop on the leaves lots of medium to suck up that water)

But again I’d wait for more experienced opinions

Thanks Miked,
I just watered with 5.6 ph water and had about 1/2 gallon of runoff per plant.
The runoff was 7.2 ph again…was 6.7ph in the feeding runoff last week, so I thought the ph issue was resolved.
I know I added too much dolomite lime to the top of my soil, so I know I probably have to add something acidic on top of my soil now, since it’s been 3 weeks with runoff around 7.0 - 7.2ph.

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hopefully someone with more experience will chime in soon, id assume since you added the lime the PH will stay up above 7.0 until it is depleted. im on the lower end with PH i watered at 6.8PH and runoff was 6.0 so im low (i dont know which is better lol) i did feed with flower neuts today though even with my high PPM’s in runoff my feed water was only 900PPM but runoff was 2500-3k still, gunna let it ride as the plants look good and healthy next 2 watering will be 6.8PH water only. just felt i had to get some flowering neuts in there because of being in week 2.5-3 into flower and i have to work 12 hour shifts the next 5 days and wont really have time to mix up neuts or water and they were ready for watering today pots were light as hell already lol maybe i was wrong but i guess we live and learn i dont ususally do EC but today i checked it in the runoff and mine is 6000 so dont feel so bad lol

id assume the PH in your runoff went up possibly because the last feeding activated more lime as i believe dolomite lime is time release if i’m not mistaken

That run off PH looks good at 6.6.

:point_up_2:I’m confused by this. An EC should read more like 4.0 and PPMs at around 2000. The input compared to the run off isn’t terrible with a 200 difference, 300 or more is a concern though. Anyway I would do a good lead inspection for pest, I thought I saw some white specs?? What medium is that? Soil likes a wet to dry cycle and a water/feed frequency with liberal run off :love_you_gesture:

i also plan on picking up some fox farms sledgehammer to flush with on my next watering i know one of the stores near me carries it i just cant remember which so ill have to stop and look tomorrow on my way to work, i should have technically used it about a week or so ago according t the feeding schedule but was just using plain PH’d water instead i guess just water doesn’t do as well I figured after 2 heavy waterings with plenty of runoff my PPM’s would be dropping down by now and PH would be increasing. Fingers crossed atm i show no signs of issues with the plants but would like to avoid any in the future as well

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So my watering and feeding was taking 2-3 hours and I realized it was because the dolomite lime was cementing on top of the soil.
I just broke up the top soil it all up and added perlite and very acidic peat moss.
Was hoping to reduce the constant 7.0 - 7.2 ph by adding more peat moss, but upon breaking up the soil I actually increased the ph runoff to 7.4 ph.
So I tried another gallon with 5.6ph, then another with 5.1 ph water and still am getting 7.2ph runoff after 3x my usual watering of 1 gallon.

I do have to say the plants are still looking great, I prune away the spotted leaves every other day, usually only 5-10 per plant.

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