how to use lime to counter mid-late stage pH drop in promix - Indoor Grows - Soil - International Cannagraphic Magazine Forums

RubeGoldberg · 03-06-2018, 06:19 PM

For the longest time, i've been an advocate of ample runoff of promix, but im starting to realize that the initial dolomite amendment might be wearing off on me as well.

At the moment my plants (week 6.5 of 9.5 week bloom) are getting around 5.3 pH runoff, in spite of ample runoff happening on a regular basis.

part of this problem is due to the fact that I feed heavy, but I'm starting to think the medium is working against me as well.

That being said.... For a top dressing, to counter the pH drop.
What type of dolomite should I be using?

I used about 2tsp of Dolopril per gallon of medium and watered it through, but runoff is still low. (I realize it takes a bit to activate)

Can I use Rapid Lime?

Also what is the best form of lime if I want to amend the promix during transplant?

FunkBomb · 03-08-2018, 12:42 AM

The best form of dolomite lime to use is the powder. It keeps the pH where it needs to be, but the only issue is that plants eat it quickly. I add it to every soil/soiless mix I make and it works wonderfully. I go with 1 cup per 1 cubic foot of media.

I run into issues sometimes when the plants eat through it too quickly. When I use 3-5 gallon containers I'll top dress with 2-3 teaspoons and then top scratch it in. Water heavily and it will make its way into the rootzone in no time.

This is what I use:

https://www.amazon.com/Dolomite-Magn...dolomite&psc=1

-Funk

Easy7 · 03-08-2018, 01:40 AM

What are you feeding the grow?

Oyster shells in the mix are more stable for buffering than lime. A pinch of agri lime in the solution will raise it. A pinch too cause that stuff is hazardous how basic it is. Seriously, a small truck load treats acres and acres.

purplepassion · 03-08-2018, 03:14 AM

Run a tea to supplement and create a partially living soil.

PaulieWaulie · 03-29-2018, 03:56 AM

What I have noticed is that my promix PH is staying very consistent. I have been re using it for a year so am on my 4th run with it now. It was 6-6.2 in the beginning and now is 6.1-6.4, I have never added dolomite lime and usually get 20% of water going in coming out for run off. Using 3G pots, and feeding PBP for the most part at a total of 600 PM ever watering, lately I have stopped PH ing the nutrients as the media ph is always so consistent no matter what. So far so good.

I am thinking my water is fairly alkaline at 220 PPM of mostly calcium carbonate (180ppm), so every watering there is a bit of buffering occurring.

troutman · 03-29-2018, 03:58 AM

If your worried about using too much pH up or down.

Test the pH of your nutrient water solution prior using it and you won't overshoot your end pH goal.

Eventually you'll get a feel of how much base or acid to use.

Douglas.Curtis · 03-29-2018, 06:15 AM

Overfeeding is probably the number one reason for low pH in the root zone. It's due to root rot.

G.O. Joe · 04-01-2018, 04:38 AM

I attributed it to the chunks of limestone in promix dissolving over time, but the peat staying acid for longer. So, I'd add extra crushed limestone or dolomite from the start. A cup of it per cubic foot.

bsgospel · 04-01-2018, 01:55 PM

I might be remembering it wrong but won't carbonates in acidic soil cause greater fluctuations in ph? Carbonates have better stability in alkaline soils, which is why gypsum is a better option/sul-po-mag in combination? Or do I have it backwards?

G.O. Joe · 04-01-2018, 02:57 PM

What is gypsum going to do for pH though. I think you mean the difference between dolomite and plain limestone of the same size. What they use is a mix of the two in pebble size. It's not quick to do anything, so promix be wetted for a week before transplanting to bring the pH up. The finer forms dissolve faster then are gone and this is the avoidable undesirable pH swinging. I have recommended the dolomite every time this has come up over the years, using the amount suggested by GH for a long time with their nutes. The dolomite in addition to having Mg takes longer to dissolve, so it's still around at the end after growing for months without transplanting.

03-06-2018, 06:19 PM	#1
RubeGoldberg Senior Member Join Date: Mar 2011 Location: the coast with the most Posts: 1,043	how to use lime to counter mid-late stage pH drop in promix For the longest time, i've been an advocate of ample runoff of promix, but im starting to realize that the initial dolomite amendment might be wearing off on me as well. At the moment my plants (week 6.5 of 9.5 week bloom) are getting around 5.3 pH runoff, in spite of ample runoff happening on a regular basis. part of this problem is due to the fact that I feed heavy, but I'm starting to think the medium is working against me as well. That being said.... For a top dressing, to counter the pH drop. What type of dolomite should I be using? I used about 2tsp of Dolopril per gallon of medium and watered it through, but runoff is still low. (I realize it takes a bit to activate) Can I use Rapid Lime? Also what is the best form of lime if I want to amend the promix during transplant? __________________ Rube's 8x600W Rube's 2 room show down. Double ended VS Single Ended w/ CMH
	Quote 1 members found this post helpful.

03-08-2018, 12:42 AM	#2
FunkBomb Power Armor rules Join Date: Mar 2006 Posts: 2,595	The best form of dolomite lime to use is the powder. It keeps the pH where it needs to be, but the only issue is that plants eat it quickly. I add it to every soil/soiless mix I make and it works wonderfully. I go with 1 cup per 1 cubic foot of media. I run into issues sometimes when the plants eat through it too quickly. When I use 3-5 gallon containers I'll top dress with 2-3 teaspoons and then top scratch it in. Water heavily and it will make its way into the rootzone in no time. This is what I use: https://www.amazon.com/Dolomite-Magn...dolomite&psc=1 -Funk __________________ Many people would sooner die than think; In fact, they do so. Bertrand Russell
	Quote

03-08-2018, 01:40 AM	#3
Easy7 Senior Member Join Date: Sep 2012 Posts: 1,575	What are you feeding the grow? Oyster shells in the mix are more stable for buffering than lime. A pinch of agri lime in the solution will raise it. A pinch too cause that stuff is hazardous how basic it is. Seriously, a small truck load treats acres and acres. __________________ This is username Easy7, NOT username EasyGoing. They say geniuses pick green
	Quote 1 members found this post helpful.

03-08-2018, 03:14 AM	#4
purplepassion Member Join Date: Feb 2009 Posts: 170	Run a tea to supplement and create a partially living soil. __________________ Urb Company Maine Tea Growers
	Quote

03-29-2018, 03:56 AM	#5
PaulieWaulie Member Join Date: Sep 2008 Location: Kanada Posts: 463	What I have noticed is that my promix PH is staying very consistent. I have been re using it for a year so am on my 4th run with it now. It was 6-6.2 in the beginning and now is 6.1-6.4, I have never added dolomite lime and usually get 20% of water going in coming out for run off. Using 3G pots, and feeding PBP for the most part at a total of 600 PM ever watering, lately I have stopped PH ing the nutrients as the media ph is always so consistent no matter what. So far so good. I am thinking my water is fairly alkaline at 220 PPM of mostly calcium carbonate (180ppm), so every watering there is a bit of buffering occurring.
	Quote 1 members found this post helpful.

03-29-2018, 03:58 AM	#6
troutman Seed Whore Join Date: Dec 2016 Location: In the Fridge Posts: 1,603	If your worried about using too much pH up or down. Test the pH of your nutrient water solution prior using it and you won't overshoot your end pH goal. Eventually you'll get a feel of how much base or acid to use. __________________ I just died.
	Quote

03-29-2018, 06:15 AM	#7
Douglas.Curtis Senior Member Join Date: Jul 2016 Location: Back in Colorado! Yaay! Posts: 2,260	Overfeeding is probably the number one reason for low pH in the root zone. It's due to root rot. __________________ "Secrets to Growing Trichome Dense Cannabis" Now Available in Print! My intentions are noble, pay no attention to my autistic lack of diplomacy.
	Quote

04-01-2018, 04:38 AM	#8
G.O. Joe Senior Member Join Date: Oct 2008 Location: Ditchweed City Posts: 1,117	I attributed it to the chunks of limestone in promix dissolving over time, but the peat staying acid for longer. So, I'd add extra crushed limestone or dolomite from the start. A cup of it per cubic foot. __________________ In the clinical field, the practical application of these substances must be awaited with the usual necessary patience. - Roger Adams Marihuana February 19, 1942
	Quote 1 members found this post helpful.

04-01-2018, 01:55 PM	#9
bsgospel Member Join Date: Apr 2014 Posts: 398	I might be remembering it wrong but won't carbonates in acidic soil cause greater fluctuations in ph? Carbonates have better stability in alkaline soils, which is why gypsum is a better option/sul-po-mag in combination? Or do I have it backwards? __________________ It's time for a revolution, but probably not in the terms that people imagine it. The word conjures up images of— a modern day version of peasants going into the street with their pitch forks to go after the bad guy who lives in a big house and we're gonna get that son-of-a-bitch and we'll take all the stuff from him and we'll give it to the workers. That's not the kind of revolution I had in mind. I thought that it might be nice if it was handled a little bit more modern and efficient way, without people getting slaughtered. It's a matter of infiltration…The people who are in control of the media, the government that run the lives of the average person in the street. They aren't doing a good job 'cause they don't really care. The potential is there in the younger generation. Right now they’re not really interested. Their political involvement is on a very superficial basis. They go out for the social aspects of a march or a rally rather than for what it could possibly accomplish. -FZ
	Quote

04-01-2018, 02:57 PM	#10
G.O. Joe Senior Member Join Date: Oct 2008 Location: Ditchweed City Posts: 1,117	What is gypsum going to do for pH though. I think you mean the difference between dolomite and plain limestone of the same size. What they use is a mix of the two in pebble size. It's not quick to do anything, so promix be wetted for a week before transplanting to bring the pH up. The finer forms dissolve faster then are gone and this is the avoidable undesirable pH swinging. I have recommended the dolomite every time this has come up over the years, using the amount suggested by GH for a long time with their nutes. The dolomite in addition to having Mg takes longer to dissolve, so it's still around at the end after growing for months without transplanting. __________________ In the clinical field, the practical application of these substances must be awaited with the usual necessary patience. - Roger Adams Marihuana February 19, 1942
	Quote 1 members found this post helpful.

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