HELP! Control the Ph swing

[Closetbeasties]

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[Hr250]

Ph water higher to compensate. Add lime to dirt next time. So if your water is neutral (ph7), and your run off is acidic (ph6 or less) then ph water to 8 going in and see what your run off is and adjust till water runs out around 6.5.

[az2000]

AHHH! I am battling a Ph swing in my dirt. Using ocean forest, FF soil trio, Ph neutral water. Flushed plants week ago to stabilize Ph, check today, it has turned acidic. What could be causing this, and how do I fix it. Thanks in advance.

What stage of life is your plant? (how many weeks since sprout?). How often do you water?

FF products seem scary to me because OF is amended with nutrients which should last 6-8 weeks. People often use the "trio" too. Then they overfeed. Or, they forget to that the soil will become exhausted, and don't feed when they should. (Then there's a gray area where you need to start feeding, but not full strength.). Plus, FF soils seem heavy, slow-drying. Maybe they're supposed to be due to their nutrient-rich nature. But, I feel like cannabis likes thorough wet/dry cycles (and more frequent than FF seems to dry).

My guess is that you're not letting it dry enough. That will acidify the soil. Sol will go through a ph swing from wet to dry. Plus, if you add ph-up to correct that, you're essentially adding more nutrients. If the soil is acidifying due to too much nutrients (which is common when people use OF plus "trio" too soon), the ph-up salts will contribute to more acidity. (The "up/down" products are typically nutrients. They just don't show it on the label because they aren't sold as nutrients.).

Not trying to discourage you. It would be good to know more details.

[az2000]

Closetbeasties, that sounds good. How dry is the soil after 3 days? I've never used OF, but from what I've read (people who do use it), it sounds like it dries slowly. I'm wondering if 10% added perlite would be enough to let it dry enough in 3 days. Does the container feel significantly light when you lift it?

It doesn't sound like you've been overfeeding. So, keeping it too wet sounds like a possibility. Flushing could have made it worse (more wet time).

Are you measuring the runoff ph? I've never thought that was too accurate unless it's done in a very precise/controlled way. (You can google for "NCSU Pour-Through Extraction Procedure." You'll find PDF describing it. There's also a slurry method described on Oregon's Only Nectar of the God's "how to" page.).

If you really have a ph problem, you can mix 3/4tsp Fertilome Hy-Yeild Horticultural Lime (hydrated lime) to 1 gal water, and pour that through the soil. I've done it before without negative consequence. It makes a fast ph change compared to carbonated limes (dolomite). It's scary to do. The water is like ph11. Hydrated lime is phytotoxic, not healthy for a plant. But... so is nutrient lockout due to acid soil. So... pick your poison. It's not something I'd do casually. Acid soil is usually due to overfeeding or keeping the soil too wet. But, if there really is a ph problem... you don't have a lot of choices. Ph-up adds salts to the soil. It's one thing to just balance a nutrient solution (although I don't think that's necessary in soil. I don't ph my nutrient solution.). But, the amount of ph-up necessary to move the soil ph is substantial. Depending on the content of the ph-up(which they don't usually publish because it's not sold as a nutrient) could cause nutrient imbalance. To me, that's a valid time to use hydrated lime. All I know is that I've done it and that strength didn't cause a problem (and did make an immediate improvement.).

[Mr.furley]

The real questions is how do your plants look? Sick? Or do they look fine and you are chasing pH in soil?