Help Please!!! PH problems... Looking for advice.

Px9023

Active Member
Hi all,

I'd appreciate any help possible. I'm in late stages of vegging. I was planning on flipping to flower in about 2 weeks my plants have been declining in health. I'm growing in soil. I have 2 in 10 gal pots and one in a 15 gal all smart pots. It is my own mix. The mix consists of 4 qt potting soil (promix), 1 quart worm castings, 1 qt composted manure, 1 tsp blood meal, 1 tsp bone meal 1 qt perlite. When initially planted into final pots the soil ph was 6.3. Every watering I Ph water to 6.2-6.4 and water when top of soil begins to be dry. I feed once every 7-10 days. I use Roots Organic Line. I'm using Buddha Grow and trinity. Cal Everything was pretty good. About 2 weeks ago I noticed some lighter lime green coloration in new top growth. I originally thought it was nitrogen deficiency or calmag. I tried upping ratios of both. As I started. I went and bought a soil ph test kit. The one with the capsuls. From that my soil seems to be about 7.0 I also bought one of the cheapie soil ph meters which says 7.0 as well. I'm not new to indoor growing but new to indoor cannabis. I tried lowering with phosphoric acid (ph down). First I made ph'ed water at about 4.6 I put 5 gallons of water through the 10 gallon pot, and 7.5 gallons through the 15 gallon. It waited a half hour and tested the soil the soil was at 7.0. So I made another solution of 3.5 ph'ed water tested after 10 minutes. Was at 6.5. Checked 30 minutes later and was at 7.0 again. So next, I added 3 tbsp granulated sulfur in the 15 gal and 2 tbsp in the 10. I know sulfur breaks down slowly. I decided to do an experiment. I made a solution of sulfuric acid and ph'ed to 2.5. Same results the soil ph rebounds to 7.0. After doing some reading I have come up with only one possible cause. I was giving cal mag pretty heavily. From my reading the magnesium can break down and leave behind a lot of salts that act as a buffer. Would everyone agree? If not what would make the soil keep on going up? What would be my best recourse? Flush soil with 3 gal ph"ed water per gallon of soil? Repot the plants with fresh soil? I have been vegging for a while don't want to loose them. I think the soil ph is causing nutrient lock. First two pictures is from 2 weeks ago second two is today. Thanks for any help or advice in advance.
 

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MustGro

Well-Known Member
I add dolomite lime to my mixes for the cal/mag in it but also to buffer the PH from the sphagnum peat moss, which is a bit too acidic. Dolomite is famous for it's ability to "sweeten" soil; keep it's PH in the "sweet" spot. I'm not sure if it's the calcium, magnesium or something else in it that does this.
I know that if you have alot of carbonates in your water they'll buffer the PH of solutions too, but not sure if that's what you're seeing.
I personally wouldn't put a 2.5 PH solution on my plants.
 

Px9023

Active Member
I add dolomite lime to my mixes for the cal/mag in it but also to buffer the PH from the sphagnum peat moss, which is a bit too acidic. Dolomite is famous for it's ability to "sweeten" soil; keep it's PH in the "sweet" spot. I'm not sure if it's the calcium, magnesium or something else in it that does this.
I know that if you have alot of carbonates in your water they'll buffer the PH of solutions too, but not sure if that's what you're seeing.
I personally wouldn't put a 2.5 PH solution on my plants.
Must grow thanks for the reply. So do you think I should flush or repot? And I'm right it looks like PH problems?
 

HydoDan

Well-Known Member
You do understand that you're basically dumping acid on your roots...
I guess flush with 6.3 and hope for the best..
 

MustGro

Well-Known Member
Must grow thanks for the reply. So do you think I should flush or repot? And I'm right it looks like PH problems?
So you're not adding any chemical nutes, just the roots organic line. I'm not familiar with it but you shouldn't have to flush an organic plant anywhere near as much as one getting chemical nutes. You're brave using composted manure inside.
I wouldn't repot; yours are 10 and 15 gallons and you could top dress with some dolomite, but it takes time to work.
What's your source water like for PPM and PH. I don't PH my outside crop (organic) because I'm afraid the chemicals will mess with the microbes.
If they're wet from a lot of flushing I'd leave them for a bit. Not worth it to add overwatering to an existing problem. How long does it take those pots to dry out?
 
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