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What is pH?

Doctor Trevor

Well-Known Member
One of my plants, Stacy, has some yellow leaves. I thought it was a magnesium deficiency and gave her CalMag. This hasn't helped as she's growing more yellow every day. And she's a few weeks away from harvesting.

This morning I checked her pH with one of those soil probes. Her pH is close to eight. I have no idea how this happened as she gets the same feeding as her sister plant (which is doing fine).

What's the best way to bring the pH down? I thought of watering her with some acidic water. The thing is, I flushed and fed her yesterday. Her soil is saturated with water; I don't want to wait a week for her soil to dry.

And help would be appreciated.
 

Frigault's Genetics

Well-Known Member
What is pH?
pH is one of the most common analyses in soil and water testing. An indication of the sample’s acidity, pH is actually a measurement of the activity of hydrogen ions in the sample.
pH measurements run on a scale from 0-14, with 7.0 considered neutral. Those solutions with a pH below 7.0 are considered acids, and those above 7.0 are designated bases. The pH scale is logarithmic, so a one unit change in pH actually reflects a ten-fold change in the acidity. For instance, orange juice (pH 4) is ten times more acidic than cottage cheese, which has a pH of 5.
Many industries rely heavily on pH for their processes to work properly, or to maintain expensive equipment. Breweries maintain the pH between 4.2 and 4.6 to keep infectious bacteria from breeding during the fermentation process. In many industrial applications, if the pH is too low the water may corrode metal equipment, but if it is too high scaling may result.
pH can be measured visually or electronically. Visual comparisons use a pH indicator whose color change reflects the pH, which is then matched to a color
standard. pH meters, such as the pH 5, simplify the pH test. A probe is placed in
the sample, and the pH is read directly from the meter.
While the meter is very easy to use, the electronics within the meter are more
complex. After the pH probe measures the millivolts of potential between the
reference electrode and the pH electrode, the meter converts this reading to pH
units using the Nernst Equation:


where Ex = constant depending upon reference electrode
R= constant
Tk = absolute temperature
n = charge of the ion (including sign)
F = constant
ai = activity of the ion

Electrode Cleaning
Because your pH electrode is susceptible to dirt and contamination, clean it
every one to three months depending on extent and condition of use.
Clean the electrode in a mild detergent solution. Wipe the probe with a soft
tissue paper. Avoid touching the glass membrane with your fingers. Rinse
thoroughly in tap water and then in distilled water. Recalibrate your meter after
cleaning the electrode.

Storage
The pH electrode should always be stored in the soaker bottle. The cap should
be tightened to prevent leaks. The soaker bottle contains a dilute solution of
potassium chloride.

Special Cleaning Tips
Salt deposit: dissolve the deposit by immersing the electrode in tap water for ten
to fifteen minutes. Then thoroughly rinse with distilled water.
Oil/grease film: wash electrode pH bulb gently in detergent solution. Rinse
electrode tip with distilled water.
Clogged reference junction: heat a diluted KC1 solution to 60-80°C. Place the
sensing part of the electrode into the heated solution for about 10 minutes.
Allow the electrode to cool in some unheated KC1 solution.
Protein deposits: prepare a 1% pepsin solution in 0.1M of HC1. Place the
electrode in the solution for five to ten minutes. Rinse the electrode with
distilled water.
I thought it was the Potentcy high
 

Frigault's Genetics

Well-Known Member
I've read in scientific study that the optimal ph for canabis was 6.2 with a smal dip towards 6 one weak and another towar 6.4 the next week but overall Ph soil at 6.2 and water at 6.2 would have an healtier effect over a 6.0 stable soil and water or a 6.5 soil and water. But many grower prefer waving in between 6.0 and 6.5 thru growing cycle.. i've had many great comment from friends looking at my canopy and complimenting hiw healthy it was at a 6.2 well balance soil.
 

Growdad420

Well-Known Member
One of my plants, Stacy, has some yellow leaves. I thought it was a magnesium deficiency and gave her CalMag. This hasn't helped as she's growing more yellow every day. And she's a few weeks away from harvesting.

This morning I checked her pH with one of those soil probes. Her pH is close to eight. I have no idea how this happened as she gets the same feeding as her sister plant (which is doing fine).

What's the best way to bring the pH down? I thought of watering her with some acidic water. The thing is, I flushed and fed her yesterday. Her soil is saturated with water; I don't want to wait a week for her soil to dry.

And help would be appreciated.
When you fed her what was the PH of the water with Nutes?
 

Doctor Trevor

Well-Known Member
When you fed her what was the PH of the water with Nutes?

I couldn't find the test kit so I just fed her the scheduled nutes.

I'm thinking of adding a little acid solution to the soil every day until the matter is resolved.
 

Frigault's Genetics

Well-Known Member
I couldn't find the test kit so I just fed her the scheduled nutes.

I'm thinking of adding a little acid solution to the soil every day until the matter is resolved.
Just water with the right solution and the right PH and instead add 20% watering to it it will eventually adjust without causing ireversible damage.. do a complete saturation with little extra and wait a little longer before watering and feeding again.
 

Frigault's Genetics

Well-Known Member
Soil PH Meter? As in those cheap probes that tell you when to water etc...? Can't get a correct reading with those, and if we talking actual soil and not a hydro like medium like coco then it has things built into it that buffers the PH and no reason to even try to measure the PH of it. Worry about the PH of water/nutrients going in being in the proper range for your medium (or your nutrients as some call for a slightly different PH according to manufacturer) , as chasing problems that are not there will create actual problems, unless your plants are showing signs of deficiencies/lockout.
There are very acurate ph reading brobes iut there. They cost 300-400 dollars. And si i'm an actual horticolturist. I can tell you that its possible to do soil testing with a normal ph pen. You need iy to be calibrated need to take sample at a few places in the pot and mix it in distiled 7.0 distilled wated to a certain part and mesur the diference in the water tested after iy has been siting and you'll know the soil ph.
 

Emilya

Member of the Month: Mar 2019 - Grow Journal of the Month: Jan 2020
Ph is one of those things that is greatly misunderstood in the growing world. First of all, please note that out in nature and indeed in indoor container organic grows, pH is not a concern. The ONLY reason we adjust pH is for our synthetic nutes, because they are locked (chelated) until we put them in a situation where the pH is between 6.2-6.8 or with hydro nutes, 5.5-6.1 pH. They are designed to break apart from their bonds and become mobile in the water/soil solution, when the pH has been adjusted properly. If you are not using these sorts of nutes, THERE IS NO REASON TO ADJUST PH.

That being said, there are confusions over how to measure pH. Do we measure the soil, the water going in or the water running out after we water?

Soil pH is set at the factory where they make it. Soil includes buffers (lime and peat) that interact with the pH of the water that comes in. Soil is designed to keep the pH within a certain range, but more importantly it is designed to make your pH DRIFT after you have watered. We say that we should adjust our pH to 6.3 in soil, but that does not mean that it stays there. When you water, the 6.3 pH water immediately starts interacting with the buffers, and the pH begins to rise. The pH does not stay at 6.3, it drifts upward toward the BASE PH of the soil, usually set to 6.8 pH or even higher. The goal is to allow your nutes to drift through the entire range of 6.3-6.8 after you have watered, so as to be able to pick up each nutrient as it becomes the most mobile in that soil. With the base pH set to 6.8, as the soil begins to dry out from top to bottom as the plant begins to use the water, that dryer soil loses the influence of the lower pH liquid and reverts back to the base pH. The pH of your container can be different in different places in that container, depending on how wet it is there.

So someone advising you to throw acidic liquids at this soil so as to neutralize it, and force it to be more acidic, is advising you wrongly. There is no reason to do this and it will be harmful to your grow if you accomplish it. The drifting ability in that soil is what makes our nutes work correctly.

When you water to saturation (runoff) you have created a column of pH adjusted water/soil saturation, and the pH of that column of water IS the Ph of the fluid you used to build it. It can be no other... there is just too much water in comparison to anything else in there... the pH of the water determines the pH of that column of water. At the moment you top off that container, its pH IS 6.3 pH.

So what about runoff? Why is it usually so different and oftentimes scarily acidic?? Think of a coffee percolator. The more water you run through, the weaker the coffee... and vice versa. At what point of runoff, 2%, 5% even 20%, are you getting an accurate number that represents the pH up above? The answer is NEVER.... the point that you stop and measure is totally random. Measuring runoff pH in soil is a total waste of time and tells you nothing about what is going on.
 

Doctor Trevor

Well-Known Member
Sorry nute water. After you add your nutes to the water ph it to 6.2. do your plants require once a week based on moisture data or just winging it?

Each plant gets a gallon of water, with nutes, once a week. The soil gets pretty dry in that time.
 
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