A question on PH

[Bluesboy]

Hey everyone, I have a quick question about pH. I've been feeding my OG Kush hybrids every other to every third watering. They all look pretty good but 2 of my 12 are showing what appears to be a dead ringer for zinc def. Now..I've been giving them micro nutrients with the grow/bloom nutrients so I don't think it's an issue of the zinc being present but I think it may be getting locked out.

I balance all my feedings to a pH of 6.3 but last night after a nice watering I tested some of my run off and it was coming in around the 5.3-5.0 zone. My meter is new and freshly calibrated, I don't see it as being inaccurate or undependable. I don't understand what could be causing the pH to flux like this but what I want to know is should I be upping the pH of my feedings so the run off isn't so low?

I was thinking if i upped my feedings to say 6.8 pH the run off would be in the 5.5-5.8 range instead of where it is now. Any advice on the approach I should take to tighten my pH would be greatly appreciated.

thanks in advance folks,

Bluesboy

 

[Weedninja]

I don't understand what could be causing the pH to flux like this but what I want to know is should I be upping the pH of my feedings so the run off isn't so low?

That's not pH flux; Your soil is very acidic(assuming your meter is correct).PH flux means that it's moving up and down. You are pouring 6.3 water into soil and it's coming out in the low 5s, which means that your soil mix is probably in the high 4s(Not good).
What are you using i.e. Fox Farm, Pro-Mix etc.?

 

[Kinderfeld]

hydro or soil?

If soil try giving them 7.5-8.0 ph'd water.

 

[Weedninja]

Zinc gets locked out under VERY alkaline(high pH) conditions BTW

 

[Syndicate]

I had a similar problem lately, soiless runoff was 4.8 with ph 6.0 water going in and I tried to fix it by watering with water adjusted with potasium silicate to bring it up to the low 8's.Runoff test a few days later still came out at 4.8.

I ended up treating them on their next watering with 6/ml hydrated lime per gallon of water, ph of this solution was really high and maxed my meter out at 10.5, runoff test the next day showed a runoff of 6.0 with 6.0 going in.

Seeing as how the ph of the RO water didn't change as it passed through the pot, can I assume that the soil is now a neutral 7?

 

[Koskesh]

Seeing as how the ph of the RO water didn't change as it passed through the pot, can I assume that the soil is now a neutral 7?

having the same problem :/ but can't seem to find hydrated lime. high ph water has not helped at all. runoff was 5.3, after 3 waterings with 7 it's still 5.3

glad to hear the lime moved the ph, would you please keep us posted on the longer term results?

 

[stinkyattic]

Syndicate- if the liquid has very low ionic strength you might not get an accurate reading on many meters.
Peat has a natural pH in the 4.5-5.5 range, approximately.
You have to re-pot frequently to manage your peat-based mix properly. That way fresh roots always find fresh soil with FRESH LIME. If your water is very soft or contains organic acids, running a low level of CalMag in your feed will help postpone the soil lime being used up.
This is a VERY common problem in soilless peat mixes and re-potting is the simplest way to stay one step ahead of it!

 

[Syndicate]

Thanks for the input Stinkyattic, repotting at this point isn't really an option as I can barely slide a piece of paper between the pots as it is...they are in 5 gallon pails and I am in the last few weeks (will probably let them go an extra week or so to try and make up for lost time).They need to be fed tonight and will check the PH runoff with a food solution,I'll add a bit of cal-mag to the mix as well.


Koskesh I hear ya on the availibility of the hydrated lime, not easy to source locally-my store guy had to make a special trip to his supplier to get it for me, I have a 50lb bag of it now and only used a coupla cups total.You could try a fine mesh dolomite, but everything I have read says it takes a long time to react, but it probably wouldn't hurt.At this point I'm not really positive I did the right thing but over the past few days the plants have started to look better and resume growth, fingers crossed and best of luck.

 

[Bluesboy]

I'm using pro-mix HP with earth juice organic nutrients. The earth juice nutrients make the pH of my water plummet when I mix it in, I then bring it back up to 6.3 and water with that solution. The water coming out is a full point under that.

 

[Syndicate]

Bluesboy You can try and adjust your PH of your a solution a bit higher say 7.0-7.3 measure the runoff from that.Just the higher PH solution for me didn't hold after it hit the soil, it might work better for you though.

 

[Bluesboy]

Thanks syndicate I'll give it a try, I'm also going to try to research a bit in the organic section to see if there is something I can blend with my promix HP to stabilize the pH of the soil.

Be good,

Bluesboy

 

[Syndicate]

-Update,

Fed the plants tonight with 800ppm, including 2ml/gallon cal mag.Adjusted the PH up 6.5, runoff was still holding at 6.0- so I guess thats where the PH of the soil wants to sit after the hydrated lime application, just hope it holds out for the next few weeks.

 

[Dr. G]

ya ive been having probs too ive been adding lime now and feeding at 6.3-6.5 this run was fine

oh and i only added lime to some and i coulnt really tell which was which in the end