dont know anything about dwc, but whats your ec and what is your light height from canopy and intensity?

Did they look like this before you pulled back? How much did you cut? Im thinking they just be hungry now, but you wont know without an EC measurement

Long time DWC grower here. how stable is your PH?

See how those little brown spots are all starting from the leaf serrations?

That's happening because there a PH imbalance between the bulk of the water leaf, and the harder to circulate to leaf margins.

Ph imbalances/swings mimic deficiency through nutrient lockout.

In veg you need to be as stable as possible around 5.5-5.8... come up to about 5.8-6, but never any higher then 6.3-6.5 during flower

Keep tabs on ppm and EC on the solution. If the solution is drifting acidic and PPM up you are definitely over feeding. Backk off a couple hundred PPM. You want to be feeding light enough that the plant is pulling nutrients out of the water faster then the water itself. The sign of this, is a slowly lowering EC/tds. And a slowly raising PH. The slowly raising PH is also what allows calcium and magnesium to become bioavailable to the plants at all.

Ph swinging up causes far less nutrient lockout in dwc then swinging down. When swinging down magnesium and calcium are the first to lockout (IIRC, been a while) and youll start seeing signs of being deficient in these nutrients. If you see the browning starting from the serrations along side the deficiency/toxicity, chances are its not actually deficiency or toxicty, but PH lockout.


Flushing out your buckets every other fill is a good idea as well.

Dwc is its own thing separate from all other methods of growing, even hydro methods. You cannot feed your plants above 1000ppm. Ideal is more like 700-900 in my experience.

Lockout damage doesnt go away on old growth btw. Just keep an eye on new growth to note if you have fixed the issue or not. Sativa leaning plants tend to be more susceptible to lockout issues and PH as well in DWC, to an exaggerated degree in DWC compared to other methods as well.

Do not feed sativa dominant plants above 650ppm unless you know the particular plant can take it either. Planst have access to nutrient at all ties in DWC. It is crucial you keep your root zone stable as possible, do not overfeed, and keep that PH in the goldilocks zones at all times. And MAKE SURE you are swinging up into the availablity of calcium and magnesium. If it's lockout not deficiency, adding extra cal-mag will compound the issue, not fix it.


Hope some of this helps!

Good stuff. Especially regarding the detail on the effect of ph imbalance on the leaf. Source? Thats the kind of info i like to know about.

Stokes said:

Good stuff. Especially regarding the detail on the effect of ph imbalance on the leaf. Source? Thats the kind of info i like to know about.

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Edit: i misunderstood the question. Just from experience, it's probably technically a calcium deficiency on the surface, but calcium deficiency is very rare in a hydro setup, especially if using tap water. I know cannabis plants have trouble circulating fluid to that section of the leaf most, it's where excessive transpiration shows symptoms. It's actually the first part of the leaf a variety of immobile nutrient issues will show.

Every time ive seen that in DWC it's a ph issue not a nutrient deficiency. Although technically, they are the same thing, but have different causes. Those stiffening, curled, but pale leaves are telling me is got a host of micronutrient issues as well. In general, when a plant is presenting like this in DWC, you're issue is going to be a unstable ph.

first chart soil availability, second for hydro.

Stokes said:

Good stuff. Especially regarding the detail on the effect of ph imbalance on the leaf. Source? Thats the kind of info i like to know about.

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Should also add (was quite baked the night i was answering this, completely misunderstood the question at first) The reason i connect the blackened leaf edges presenting so fast as a PH issue over actual nutrient deficiency, is because calcium is an immobile nutrient, and how calcium deficiency presents with lockout vs real deficiency can be a dangerous place to be in DWC. A PH swing down in DWC, It's usually caused by overfeeding, but the plant will begin to display signs of calcium and magnesium deficiency, prompting you to add even more if not experienced, further amplifying the problem. Being able to identify the difference between the two is absolutely mission critical when growing sativas in DWC.

The only way an immobile nutrient deficiency can even present so quickly is if it in fact a total lockout through PH which effects even the immobile nutrients already in place being used within the plant.

Examining what PH lockout is at the biochemical level and in simple terms: Actual deficiency will present and build over time with an immobile nutrient. However a sudden PH swing can even prevent the plant from processing and using the nutrients it has already taken up. Some nutrients stored, should the acidic swing be rapid or deep enough, can actually change their molecular state from an acetate, to a hydrochloric salt within the plant. Often this changes the fundamental properties of the compound in question. When calcium and magnesium, already processed and stored, immobile nutrients (i actually dont remember if magnesium is mobile or immobile), changes from an acetate to a hydrochloric salt within the plant, the effect is the same as the calcium suddenly vanishing. And it being an immobile nutrient, once the damage is done, the damage is done.

Just in case someone reading doesnt know what immobile or mobile means: Some compounds, like all plant usable forms of nitrogen, are considered mobile, the plant can move it around. It can choose to let lower leaves die and move them to a new position within the plant. Plants can recover physically from amending a mobile nutrient deficiency. Immobile nutrients like calcium, once in place,, cannot be altered or repurposed directly by the plant. This is why immobile nutrient damage is not repairable, you can only improve the vitality of the new growth that isnt fully developed yet.

Those dark leaf edges are actually late stage calcium/magnesium deficiency signs. If this happened in a single nutrient cycle, it's only possible that it was a PH issue.

Overfeeding in DWC tends to present as burnt tips, not margins, and plants tend to become very dark green with a leathery and textured appearance to the leaves and the vascular ridges. Often becoming glossy as well.

I would be willing to bet money, the OP's PH just drifted too low too fast because the plant was pulling water faster then it was grabbing the solids dissolved in it, creating run-away acidification, locking out immobile nutrients and triggering, in very short order, what looks like a host of deficiencies.

Stokes said:

dont know anything about dwc, but whats your ec and what is your light height from canopy and intensity?

Did they look like this before you pulled back? How much did you cut? Im thinking they just be hungry now, but you wont know without an EC measurement

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Thank you for taking the time to give me your input. I'm going to purchase an ec/ppm reader - I've just been using a pH reader up to this point. If you know a good resource to use as an ec/ppm guide, please let me know. Either way, thanks again!

I personally use the apera ph/ec pens and have no complaints. Bluelab makes quality products. Ive had my eye on their truncheon for a minute. Its straight forward to use them, just make sure you buy some of the storage solution so you take care of your tips.

brendoneill said:

Thank you for taking the time to give me your input. I'm going to purchase an ec/ppm reader - I've just been using a pH reader up to this point. If you know a good resource to use as an ec/ppm guide, please let me know. Either way, thanks again!

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