This is incorrect,... run-off is a lousy way to test pH to begin with in soil (conditionally soilless too), it's not an accurate representation of the actual pH in the root zone...
First of all, pH can vary place to place within a pot due to microbial activity and root exudates, nute build-up or lack of, and other factors... This is why direct in-pot measuring is the best way to test it,... slurry a close second but very impractical and damaging to the roots, having to mine up enough soil from mid-pot zone...
Run-off collected from the first seeping is literally concentrated, analogous to making coffee with a cone filter... This is one reason why this first batch of run-off isn't to be trusted..
Secondly, to get even a ball park estimate of soil pH via run-off, you need to use pure water, low ppm, no pH adjusting...This assures no influencing buffering action between the water and what-all is in the pot that's in the equation, so to speak. Anything you do to alter the buffering chemistry of the water and therefore pH will skew the accuracy of results. Pouring in pH adjusted water causes interactions with pH buffering, and what comes out is the net result of all this messy chemistry, not the "snap shot" of the true pH...
Run-off testing at best, even using the method in the Infirmary Sticky article section, will only really tell you if it's more or less OK, or badly off enough to indicate corrective measure to be taken.. I have tried and tested this myself with pots, confirmed with both slurry tests and pH probe (not a meter, liquids only on them) made to test directly....
Roo, cool T's adversely affect many nutrients uptake and transport, P and micronutes in particular... Looking at those leaves, it screams P defc. which makes sense, due to in part at least the lower than OK temps.... Auto's especially do not like cool T's, it really slows them down,... stunts them, poor bud development...
You may also have some of what's called antagonistic uptake issues, where too much of one nute element interferes with the uptake of another(s).. This can happen well before actual toxicity levels are reached. Have a look in the Infirmary section, the Defc, Pic Depot diagnostic thread, and go to page 2 midway down and check out the charts on this,...
Knock off the epsoms, that unnecessary unless you have either Mg or S defc., which you don't that I can see... Be sparing with the CaliMagic too, your base nutes cover Ca/Mg well enough generally, and you're not in pure coco... true soil will also have lime in it (Ca source)...
pH adjust you feed solution last, not the water itself before... the nutes will alter the pH, so that's why you adjust if needed last -
At 360ppm, I strongly recommend you cut that tap water with pure water, RO/Di, or even those self-fill units at stores... I do this myself even for my outdoor girls, the tap water here is hard as hell! I like to get the net ppm down to around 150...
Sodium levels are also too nasty! It's toxic at low levels for cannabis, and cumulatively it can build up in there and cause problems... the plant doesn't really use Na at all, so what goes in, stays in!
...looks like you have enough P going in... switch to Tiger Bloom now... things can get wonky if you start chucking in multiple sources of nutes, top dressing, etc,... and remember organic stuff takes time to become available, and you need warm T's and good microbial activity to make that happen properly...
Have you calibrated your pH meter recently, and kept it from drying out? They are sensitive instruments, easily knocked off calibration or damaged (dry-outs can ruin them potentially)... This is a must-do mate, or you'll be getting bogus info and acting on it! I've lost count over the years how many folks flailed around with issues, only to find out the key link to the problem was bad readings off their gear! ....They also need a storage solution made to preserve the electrode bulbs function while not in use....
TDS/EC meters need it too, but much less often,.. Both need to be fullt rinsed before storing, never put away "dirty"
With all this going on, it's hard to be sure your soil is too acidic, but it's a fair bet regardless... This can also lockout P, BTW....
Stay away from Fuxfarms soils, they are proven losers anymore for what was once a good brand. I have measured bag after bag in the low 5's!That is instant shit-show pH... lots of bummed out growers learn the hard way... They have hodge podge sourcing all over, a lucky few get OK bags, the rest get garbage....
The tea you make, from earth worm castings (EWC)? I ask because you need some sort of microbial inputs with the right cast of characters going to to work the goods,... inoculants are a smart thing to include here....
I have soil pen, I've done slurry, I've done runoff. Slurry and soil pH pen/probe being the worst, imo. When using water that is your target pH, imo runoff is close second to just squeezing enough liquid out of the medium itself to test. When doing back to back minor adjustments to alter a mediums ph (hopefully not for a pot with a plant in it), squeeze/runoff has proven fast, accurate and no questionable readings (ever, since I am doing ~a lot of them I 'got better' at it), which alone is much more than I can say for my soil pen also biggest buffer of medium. All that you need is a $10 regular pH pen (calibrated), is another great thing about this and most of us already have that or can afford it.
With the plant in the pot, runoff is fine/great when using water at your 'target' (the pH you want to be) pH, watering (already saturated medium), slowly and testing starting and ending water for any fluxuation that may indicate 'the coffee filter effect' is taking effect would be a good thing to do. Taking out just enough medium carefully will not harm the plant in any meaningful way. Again, all that you need is a $10 regular pH pen (calibrated), is another great thing about this and most of us already have that or can afford it.
Your soil needs to be well saturated for at least a couple hours prior to using any testing method, imo, and the more diverse the medium, the longer I would let it be wet before testing. You for sure don't want the coffee filter effect mentioned in the previous post, it will be caused by watering to fast and/or the medium being to dry prior to starting runoff test.
here is an auto, outside,in the shade all day, with near freezing temps at night. (The one in the back has had bad pH for a long time).
Last edited:
OF 30% regular bag top soil 30%
