PH in pro mix using dolomitic lime

Dr.B · Jul 19, 2020

As some of you may know, I've been teaching myself about media pH and alkaline buffering. I recently started mixing 2 tblsp dolomitic lime per gallon of promix hp. w/ 1 gallon of perlite to every 3 gallons of promix/lime.

I start prepping the media two weeks in advance to allow the lime to activate. Before planting the cups are flushed down to 0.8 EC left to dry and then fed at pH 5.9/EC 1.2. after feeding the media is testing at a pH of 6.5, leech water pH 6.1 EC 1.0...

Mostly I have happy plants but the clone cups are testing at around 6.8... giving me problems every couple days. I think they got a higher concentration of lime... I'm going to top dress those cups with a little straight pro mix at the next watering, hopefully that brings the pH in line with the other plants. I plan to continue watering in at 5.9 as long as everything stays consistent.

My question; Can anyone provide a little insight on what I've done here and whether or not my chosen course is the best one?

Thanks!

D

LittleDabbie · Jul 19, 2020

Doesn't promix already come buffered with lime? if your adding more when you water it raises the ph of the soil.

Stop adding it :P

PH down till your root zone ph comes out closer to target.

Dr.B · Jul 19, 2020

LittleDabbie said:
Doesn't promix already come buffered with lime? if your adding more when you water it raises the ph of the soil.

Stop adding it :P

PH down till your root zone ph comes out closer to target.

Pro mix starts at around 5.5 - 5.9. I've been adding lime in an effort to get around the pH lockout I tend to hit in late flower. My thought is, start higher, water lower. Test regularly and adjust as needed/if needed.

6.5 is good! With 6.0 - 6.1 leech... It was my target. Lol 6.8 is surprising is all...

At any point will that amount of lime bring the pH of the media above 7 if I'm consistent in watering in at the appropriate pH?

Gotta roll with it, it is an experiment after all, no point in stopping now. If I fail the lime goes away or gets cut in half...

Dr.B · Jul 19, 2020

Dr.B said:
Pro mix starts at around 5.5 - 5.9. I've been adding lime in an effort to get around the pH lockout I tend to hit in late flower. My thought is, start higher, water lower. Test regularly and adjust as needed/if needed.

6.5 is good! With 6.0 - 6.1 leech... It was my target. Lol 6.8 is surprising is all...

At any point will that amount of lime bring the pH of the media above 7 if I'm consistent in watering in at the appropriate pH.

Gotta roll with it, it is an experiment after all, no point in stopping now. If I fail the lime goes away or gets cut in half...

Unless I'm just flat out wrong lol.

LittleDabbie · Jul 19, 2020

Dr.B said:
Pro mix starts at around 5.5 - 5.9. I've been adding lime in an effort to get around the pH lockout I tend to hit in late flower. My thought is, start higher, water lower. Test regularly and adjust as needed/if needed.

6.5 is good! With 6.0 - 6.1 leech... It was my target. Lol 6.8 is surprising is all...

At any point will that amount of lime bring the pH of the media above 7 if I'm consistent in watering in at the appropriate pH.

Gotta roll with it, it is an experiment after all, no point in stopping now. If I fail the lime goes away or gets cut in half...

In with some popcorn :D

Aqua Man · Jul 19, 2020

Dr.B said:
Unless I'm just flat out wrong lol.

Your right... Try cutting the lime in half.

Ppl need to remember that we need to build our soil to match the nutrients and source water we use.

Dr.B · Jul 19, 2020

Rog

Aqua Man said:
Your right... Try cutting the lime in half.

Ppl need to remember that we need to build our soil to match the nutrients and source water we use.

Roger that. Less lime.

Thats exactly what I'm attempting to do lol

Dr.B · Jul 19, 2020

Top dressing with unaltered pro mix? Good idea to lower the pH in the cups testing higher?

Dr.B · Jul 19, 2020

At those numbers. 6.5 media pH. What do you think my best input pH should be starting out?

Aqua Man · Jul 19, 2020

Dr.B said:
Top dressing with unaltered pro mix? Good idea to lower the pH in the cups testing higher?

Straight peat is what I am familiar with but iron sulfate will work... Don't ask me the dose to use though I have no clue

Dr.B · Jul 19, 2020

(Thanks guys, I tend to "learn" myself quietly into a corner or blind alley from time to time... I got myself a little lost here. Way off my numbers from the first two years... I really would like to master this approach and work from the other end of the pH scale, if not find the balance that I'm after)

You're help is appreciated!

LittleDabbie · Jul 19, 2020

You want a ph of the soil 6-.6.5 so imput ph should be between.. get this :P 6 and 6.5 If your gonna keep adding Lime, I would ph closer to 6, if the run off comes out at a 7 then next water ph to 5.5 and check run off again.

MIMedGrower · Jul 19, 2020

10 Must-Know Growing Media Facts

From managing nutrient levels to addressing common issues like mold and odor, discover essential insights on growing media with our guide to 10 must-know facts.

www.pthorticulture.com

MIMedGrower · Jul 19, 2020

Also pro mix website warns to check bales for over lime. Sometimes clumps get stuck in the mixer they say and too much lime results so check ph after a week watered in a cup with pour through method or up front with slurry method for actual medium ph. Dry new pro mix will always read low until lime activates.

Also the ec up front is a balanced fertilizer charge not on american labels according to pro mix. So you can start and transplant without nutes and go a week or two before need to feed.

The link i added above is very informative.

Beachwalker · Jul 19, 2020

Dr.B said:
As some of you may know, I've been teaching myself about media pH and alkaline buffering. I recently started mixing 2 tblsp dolomitic lime per gallon of promix hp. w/ 1 gallon of perlite to every 3 gallons of promix/lime.

I start prepping the media two weeks in advance to allow the lime to activate. Before planting the cups are flushed down to 0.8 EC left to dry and then fed at pH 5.9/EC 1.2. after feeding the media is testing at a pH of 6.5, leech water pH 6.1 EC 1.0...

Mostly I have happy plants but the clone cups are testing at around 6.8... giving me problems every couple days. I think they got a higher concentration of lime... I'm going to top dress those cups with a little straight pro mix at the next watering, hopefully that brings the pH in line with the other plants. I plan to continue watering in at 5.9 as long as everything stays consistent.

My question; Can anyone provide a little insight on what I've done here and whether or not my chosen course is the best one?

Thanks!

D

You may have a disaster brewing!? I did the same thing, put Dolomite in my pro mix and the pH was through the roof and I had trouble the whole grow with various lockouts, I never did get it below 7.2 the whole grow

Dr.B · Jul 19, 2020

The lime is in... Lol. I have no intention of adding more to this mix. I intend to increase the ratio of pro mix to lime going forward in transplants to come.. . Just need to deal with it appropriately. Its all educated guessing on my end. In the spirit of learning.. savant style! (Gemini)

I'll keep watering in around 6.0 then lol unless MIMedGrower's post tells me otherwise.

Thank you!

Dr.B · Jul 19, 2020

Beachwalker said:
You may have a disaster!? I did the same thing, put Dolomite in my pro mix and the pH was through the roof and I had trouble the whole grow with various lockouts, I never did get it below 7.2 the whole grow

Fuck lol

LittleDabbie · Jul 19, 2020

Beachwalker said:
You may have a disaster!? I did the same thing, put Dolomite in my pro mix and the pH was through the roof and I had trouble the whole grow with various lockouts, I never did get it below 7.2 the whole grow

ruh Roh.

Dr.B · Jul 19, 2020

Beachwalker said:
You may have a disaster!? I did the same thing, put Dolomite in my pro mix and the pH was through the roof and I had trouble the whole grow with various lockouts, I never did get it below 7.2 the whole grow

Well, they are not in final pots yet... The flowering plant is happy. Shes in a similar mix... Its just the five cups, cbd strain out of 10 plants at various stages.

I dont think I overdid it by that much...

In the spirit of learning...

Beachwalker · Jul 19, 2020

Dr.B said:
Well, they are not in final pots yet... The flowering plant is happy. Shes in a similar mix... Its just the five cups, cbd strain out of 10 plants at various stages.

I dont think I overdid it by that much...

In the spirit of learning...

Also I would have trouble believing that it comes out of the bael at 5.5 their website says 6.2

those 10 things on that list that mr. Michigan just gave you is very good read, he gave me that a while ago and I still have it saved, very informative! Good luck

PH in pro mix using dolomitic lime

PH in pro mix using dolomitic lime

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10 Must-Know Growing Media Facts

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