Organic Living Soil - High PH

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Hello All!

New grower from Canada. I've been gardening for years, and growing mostly hot peppers and microgreens for at least a decade. This is my first Cannabis grow (autoflower Sour Maui ).

I mixed a standard soil recipe consisting of 1/3 Promix HP, 1/3 compost/worm castings and 1/3 perlite. I added some inoculated biochar, Mykos and Fish Shit microbes, which I've been including in every second watering. I let the soil cook for 5 weeks and tested PH throughout, which averaged around 6.5 (+/- 0.2). I water with Distilled water and check PH every time, which is usually between 6.3 and 6.6.

My plants showed really healthy growth, tight internodal spacing and one of them even reached 5 feet tall! The buds grew to a nice size and everything was fine. Then I started noticing all kinds of deficiencies on the leaves in mid to late flower. Brown spots, discoloration, edges burning, etc. I had just top dressed with Gaia Green 2:8:4 Bloom 3 weeks earlier and recharged the microbes throughout, so this didn't make sense.

I suspected a PH issue and decided to test the soil PH...and it came out at 7.8 and the runoff tested at 7.7. I'm testing with a well calibrated Apera pen (calibrate every watering just for good measure). I repeated the test twice in 3 pots.

What would be causing such a high PH in soil given that I am watering with much lower PH'd water, and started with a soil at 6.5?

I'll get a decent harvest, but want to avoid such high PH for the next grow.

Would love to hear from experienced growers, and thanks for your time!

Julien
 
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There's just not enough information here to really know what's going on. I would suggest a soil test so you can figure out what your cations are that are pushing up your pH. Microbes can raise pH too, though I'd be shocked if a microbial product caused that large of an increase.

If you can avoid distilled water that would be an improvement too, or at least buffer it with something prior to watering.
 
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