Weird pH issue.

Offmymeds

Offmymeds

Well-Known Member
I just flipped my 2 girls yesterday after 7 weeks. I noticed the pH runoff dropping in my coco/perlite mix and decided to test the runoff of the plants individually instead of the common runoff.

Plant 1 pH came out at 5.76. Plant 2 runoff was 4.0! The plants, of course, are using the same medium and nutes. They both look healthy but plant 2 has always been a little behind plant 1 and is a little bushier.

The roots are very healthy in plant 2 so no rot taking the pH down.

What in the world is going on? Why would the pH drop so much more in one healthy looking plant over another?

BTW, it took about 2.5 gallons of nutes at 6.2 to get the pH runoff to 5.5 in plant 2.
 
tstick

tstick

Well-Known Member
I had the same issue recently. I dealt with it by placing my 2-gallon garden pot inside a 3-gallon bucket and then watering it with water that I had pH'd to 8.0, until the water level was all the way up to the soil line. I let it soak for a few minutes. Then I pulled the 2-gallon garden pot out of the 3-gallon bucket and allowed it to drain. After the 2-gallon pots had been dripping for awhile, I collected a test vile of the runoff water and tested it. The first run was still showing a pH in the 5's, so I repeated the process a second time. After the second time of leaching the pots this way, the runoff test started to indicate the pH was finally going up into the 6's.

I top-dressed the pots with a bit of dolomite lime and I am continuing to water with water that has been adjusted to 7.0 pH. I'm going to continue to do runoff and slurry tests from here on out, but I think the pH is under control now.

I have also adjusted my potting mix with some dolomite lime (1 TBSP per gallon of soil) and bio-char (1 part bio-char to 12 parts soil).

I don't know why the pH would jump so much, but there was some component to my soil mix that made the pH drop. It might have been the Coco Loco I added...Or, it might have been something in the organic, powdered ferts I mixed in....but it's the same mix I have been using for years without any issues....weird. Anyway...Good luck. I hope you get your grow dialed in!
 
Offmymeds

Offmymeds

Well-Known Member
tstick said:
I had the same issue recently. I dealt with it by placing my 2-gallon garden pot inside a 3-gallon bucket and then watering it with water that I had pH'd to 8.0, until the water level was all the way up to the soil line. I let it soak for a few minutes. Then I pulled the 2-gallon garden pot out of the 3-gallon bucket and allowed it to drain. After the 2-gallon pots had been dripping for awhile, I collected a test vile of the runoff water and tested it. The first run was still showing a pH in the 5's, so I repeated the process a second time. After the second time of leaching the pots this way, the runoff test started to indicate the pH was finally going up into the 6's.

I top-dressed the pots with a bit of dolomite lime and I am continuing to water with water that has been adjusted to 7.0 pH. I'm going to continue to do runoff and slurry tests from here on out, but I think the pH is under control now.

I have also adjusted my potting mix with some dolomite lime (1 TBSP per gallon of soil) and bio-char (1 part bio-char to 12 parts soil).

I don't know why the pH would jump so much, but there was some component to my soil mix that made the pH drop. It might have been the Coco Loco I added...Or, it might have been something in the organic, powdered ferts I mixed in....but it's the same mix I have been using for years without any issues....weird. Anyway...Good luck. I hope you get your grow dialed in!
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Thank you. I'm bewildered. The plants look great. It came up pretty quickly too. I'm wondering if a small ant colony died inside that plant as I used borac acid to kill ants in the closet right next to the plants. I have diatomaceous earth spread but the ants don't care. I think I'll add some enzymes I have sitting around in case there is any organic rot.
 
tstick

tstick

Well-Known Member
Well in my experience, if I hadn't checked the runoff and seen the low pH, I would have probably just assumed that the plants were hungry and fed them -which would have only made the problem worse. While a runoff test may not be ideal, in my case, it was the thing that led me to a way to try and fix the problem. I can't tell you if the pH is 6.2 or 5.8 or anything specific, but when the pH of ANY test shows 4.0, then you'd be best advised to look into it before running for the cal-mag. :)

I don't know what's worse -using a cheap pH pen or using a runoff or slurry test. but in my case, I had the GH test drops and so that's what I used.
 
Hollatchaboy

Hollatchaboy

Well-Known Member
tstick said:
Well in my experience, if I hadn't checked the runoff and seen the low pH, I would have probably just assumed that the plants were hungry and fed them -which would have only made the problem worse. While a runoff test may not be ideal, in my case, it was the thing that led me to a way to try and fix the problem. I can't tell you if the pH is 6.2 or 5.8 or anything specific, but when the pH of ANY test shows 4.0, then you'd be best advised to look into it before running for the cal-mag. :)

I don't know what's worse -using a cheap pH pen or using a runoff or slurry test. but in my case, I had the GH test drops and so that's what I used.
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The thing is, if you're in coco, not enough fertigation to runoff can cause a salt buildup. That buildup of salt, will cause the ph to drop. Ime, enough fertigations with sufficient runoff, have made it that I've never had to measure runoff pH or ec.
 
curious2garden

curious2garden

Well-Known Mod
Staff member
Offmymeds said:
Apparently the issue was due to decaying ants in the coco. The ants started coming out in the runoff and the pH has bounced right back.

View attachment 5341742
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Makes sense ants not only use formic acid as protection but it's a byproduct of their decomposition. Talk about natural pH down LOL certainly an unique soil amendment. Thank you for reporting back.
 
Offmymeds

Offmymeds

Well-Known Member
curious2garden said:
Makes sense ants not only use formic acid as protection but it's a byproduct of their decomposition. Talk about natural pH down LOL certainly an unique soil amendment. Thank you for reporting back.
Click to expand...
This is one of the things I love about this site. The breadth of knowledge from the users is amazing.
 
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