Difference between nutrient lock and nutrient deficiency

So I can’t tell if I have nutrient lock causing a nitrogen deficiency, or just a straight up nitrogen def. This Candy Kush Auto I’ve been doing has been running great except until recently. It started getting yellow leaves all over, on the top, middle, and bottom of the plant. I had issues regulating my soil pH after I transplanted it into a 7 gallon pot on day 51. Runoff pH reading went from Alkaline 7.5-8 (amended with too much lime) to a little too acidic (5.5-5.8) after transplant. Also my ppms became hard to read after then too always coming out on the low side around 600-800ppms. My soils ppms are low from what I can tell on the runoff its been around 600 the past few watering, I have a meter that says my soil pH is around 6.5-7 so that should be good but my runoff will say its more around 6.0 maybe even in the 5’s. Should I flush or feed? Here are some pictures and some of my notes for the grow (please reference note screenshots for more info)


Is it possible to have nutrient lock but still be reading low ppms from runoff?

Lock will start on any growth but usually around top flower fan leafs get burnt and brown back from edge

Nutrient need will begin in lower growth and cannibalize the leaves from there up until it’s rectified

1 Like

She looks hungry to me


Every one of those cheap PH meters says 7, same with the one I used twice and tossed it.
You will need a proper PH meter and tds meter, TDS meter is cheap on Amazon.


This is the most suggested around here for a low cost meter.
If this isn’t the correct seller or model, someone will mention it.


Yeah looks hungry. Trash that pH meter. I use Apera. Its not cheap but our flowers are worth it. I’d imagine shes hungry and the pH is prob off.

In nature, the yellowing starts at the bottom of the plant and works its way slowly to the top. Just like trees in the fall, the yellow leaves fall to the ground. In some respects, what you have going on there represents the changes in nature because your plant is flowering and approaching senescence or the last phases of life.
However, it doesnt have to go that way when you play god. You can adjust nutrients and ph, keep ideal environment and flow a tad more N into the feed to keep the plant from cannibalizing itself. If you have a reading of 600 ppm thats quite low for a flowering plant… you can afford to bump that up… dont forget to continue with some N too… it still needs it!
One more thing… what water are you using and what is its ppm? Remember that if your starting ph is say… 150 that is subtracted from the ppm of the food you add right? So a reading of 600 will only be 450 ppm of useful nutrients. That plant should likely see not less than 750 to 800 ppm now.


Thanks, dude for covering the points that needed addressing. Couldn’t say it better.

Lose that probe meter ASAP!


I have an RO filter for my house so I’ve been giving them RO water since day one. The pH straight from the tap is usually 6.0-6.5. When I feed I use the Fox Farms trio and I use Baking soda as a pH up instead of the General hydroponics stuff. Since I should be feeding but also my pH might be a little out of wack how should I go about correcting my pH would you say because if i’m flushing to correct the pH then my feed problem will probably get worse. Should I feed for another water or two and then give it a solid flush or should I just give it a flush and then a good feed for a few waters after?

If it were me and I had a ph problem, I would flush with straight PHd water to the correct ph. Flush really well!!! Get all the salts out of your medium as best you can, go so far as to test your runoff, dont stop flushing until you get the results you want in your tests. Then on the last flush add food to the water to the correct amount for the plant and test it…ph as needed. And water your plants.

1 Like

How can you spot nutrient lockout?