420 Magazine's Official Girl Scout Cookies Comparative Grow By Beez0404

I feed really slowly and stop when I see the first bit of runoff. My medium has organic garden lime in it. And to answer your question I do not measure the soil pH or the pH of the runoff. Is that something I need to be doing?
 
Just an FYI, runoff pH is not a thing (unless you're doing the complicated "pour through" test). A slurry test (with distilled water) is the way to see what the pH of your peat mix is.

In case you've never done one:
Take samples from a few different places (dig down a bit rather than just use the top) and add an equivalent amount of distilled water as grams of soil (10 grams of soil, add 10ml water). If that doesn't make a slurry, use enough to make a stirrable thick slurry.

Stir it up, wait 15 minutes, stir again. Do that for at least an hour (longer is better), and then put your calibrated pH stick in the water. That's the pH of your medium.
 
So are you saying to take sample from a few different places and combine said samples into one sample that will eventually be tested with my pH pen?

Is the weight of the sample measured when the soil is towards the dry side needing to be watered? Or do I extract the sample a day or so after watering it?
 
I agree with @InTheShed that the soil slurry method using distilled water gives you the best idea about what is going on with media pH. The downside to this method is that you have to disturb the rootzone to get a sample that is not just surface material.

If you test the pH of your runoff vs feed it can give you some info even though it is not nearly as useful as the slurry test. Since the pH of the soil solution can drift over time you can get a general idea of what direction that drift is and how far its moving if you know the pH of your starting nutrient and the pH of your runoff. This is not a great way to diagnose a particular issue, just a way to see if the system is in a state of relative pH stability between feedings. If your runoff pH is similar to the feed pH that's good, if there is a big difference then I'd look at things like a slurry test to get more info. I would not use runoff pH to make decisions but in my experience lloking at the difference between the pH of your input and output is a good indicator of how the system is maintaining itself.
 
I originally was measuring the PH in the runoff but stopped since I wasn't having any issues. Might be interesting to see what mine reads this morning. I will post afterwards.
 
Well since I don't have distilled water on hand and I'm basically a lazy gardener I'll take a sample of the runoff next time I feed the plants in the next day or so and see where that pH is sitting and go from there. I know going in the pH will always be between 6.2 and 6.6 so hopefully with the Organic garden lime in the mix the pH of the runoff will be close to those numbers.
 
beez0404 said:
Is the weight of the sample measured when the soil is towards the dry side needing to be watered? Or do I extract the sample a day or so after watering it?
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On the dry side so the water in your nutes doesn't throw off the result.

I think there are too many variables with runoff pH to make it useful, especially since there is no need for you to pH adjust the input.
 
I might be a little anal but unless I'm growing in Clackamas Coots organic soil I always balance the pH of my input to between 6.2 and 6.7 It's a simple step that takes but a moment and as important as the pH level is why not do it is how I see it. I texted Lisa and asked her to pick me up a bottle of distilled water on her way home from kayaking. The plants would most likely be fed and watered on Saturday or Sunday so I can harvest a little medium and see what's going on. Am I right in figuring that whatever is going on in one is going on in all four? So one sample is sufficient?
 
Here is what I had today in Coco medium. Not much of a change in the Ph.

Input: 750ml of solution - Total starting 1510 ppm (nutrients 1020 ppm, tap water 145 ppm, Cal-Mag and Terpinator 345 ppm) with Ph 6.2.

#1 Output: 70 ml - 900 ppm Ph 6.2
#2 Output: 95 ml - 1070 ppm Ph 6.0
 
Girl Scout Cookies update for today at day 54 from sprout.

The girls continue to look good and healthy just not seeing much growth. I've started a light bending of the branches
I used a UV lens over my cell phone lens for the photo.
20210604_121722.jpg

20210604_121722.jpg

  • Media owner beez0404
  • Date added
Girl Scout cookies day 54 from Sprout
 
beez0404 said:
I always balance the pH of my input to between 6.2 and 6.7 It's a simple step that takes but a moment and as important as the pH level is why not do it is how I see it.
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Whatever you're comfortable with. That said, anyone mixing their owns medium should be slurry testing it when they're done, as you may have too much or not enough lime in there to set the pH correctly (for peat that would be in the high 5's, vs. the low 4's where sphagnum peat actually is).

Other than in hydro/coco/hempy, changing the pH of your nutes does not modify the pH of your substrate, nor does it enable your plants to take up nutrients in a substrate with a poorly set pH at its inception.
beez0404 said:
one sample is sufficient?
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As long as they are in the same mix with the same nutes and the same age, one sample is sufficient.
 
So let's say for the sake of discussion that the slurry test reveals that the pH is too high or too low is that something that can be permanently fixed?
 
And if someone had a 40 gallon tote with say 30 unused gallons of medium made using the same recipe could said 30 gallons be tested PRIOR to use using the slurry test? This 30 gallons was mixed up about 2 weeks ago.
 
beez0404 said:
So let's say for the sake of discussion that the slurry test reveals that the pH is too high or too low is that something that can be permanently fixed?
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For the sake of discussion, yes. There are a number of methods including soaking the medium in different solutions depending on the answer. The other method might not be available if you need to stick to the Rx Blend nutes, as it involves changing the type of nitrogen being fed to the plants, depending on whether you need to raise or lower the pH.

beez0404 said:
could said 30 gallons be tested PRIOR to use using the slurry test?
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Absolutely, and every batch should be tested about a week after wetting and mixing (to allow the lime to dissolve into the mix). Too low? Add lime. Too high? Add more peat and perlite. Either way, remix, and retest.

However, the pH of your medium will change over time related to the alkaline content of your water, the nitrogen source of your nutes, and how long the plant has been in the pot.
 
Good Lord, when did it all get so complicated? :(
 
Yeah, I'm sticking with the Rx Blend nutrients through the comparative grow at the very least. They were kind enough to sponsor me so I am going to be loyal to them. Probably nothing at all wrong with the nutrients, I probably mixed a batch of homemade medium with too much or too little lime in it.
 
beez0404 said:
Good Lord, when did it all get so complicated?
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When you started mixing your own ProMix HP. They do the science so you don't have to. ;)

beez0404 said:
I probably mixed a batch of homemade medium with too much or too little lime in it.
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A little distilled water and a bit of stirring will get you that answer!
 
Alright, I have distilled water and have been wondering wouldn't it be a more accurate test if the medium used was from the actual plants? I mean do I need more then like a teaspoon of medium to complete the test? Could I take a little from two different pots and mix it together? How many grams of medium mixed with how many milliliters of distilled water? Am I looking for mud? Peanut butter consistency? Milkshake? Nasty brown water?
 
InTheShed said:
When you started mixing your own ProMix HP. They do the science so you don't have to. ;)
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Hey I did my due diligence and feel I have a pretty darn good ProMix knock off.
 
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