PH and PPM explained by member PeeJay

Cannafan;1976134 said:

Here is an excellent read sent to me by PeeJay regarding my question on PPM/PH
I now understand Parts per Million (PPM) which is going to help me with a lot of things here regarding my water, not just my grow.
Thank you PeeJay! Not only for the information, but the time you spent on it!

PH and PPM:
I'll do as best I can with this question, putting it into laymen's terms. pH is a measure of hydrogen ion concentration. At 7.0 the solution is neither an acid nor a base. Below 7.0 things become more acidic. Above 7.0 things become increasingly base.

PPM is a measure of the minerals and stuff in water, or nutrients combined with the water. In general, the two biggest contributors to PPM in water from a well or the tap are calcium and magnesium. Things like selenium, copper, iron, and chlorine are all in water too. The more of these things that are in the water or water nutrient mix, the higher the PPM (parts per million.) When you dip a meter in water or water nutrient mix, it tells you how much other stuff is in the water besides just pure water - water is only hydrogen and oxygen stuck together. The PPM meter does not tell you anything about how much of each thing is in the water. It just tells you how much non-water chemicals are in solution with the water. If your water comes from a limestone aquifer it has more calcium in it, for example, but the meter won't tell you that. It only tells you how much stuff is dissolved in the water all lumped together.

Ok, some people, and especially hydroponics growers, measure the PPM of the water after adding nutrients. This is a way of knowing how much nutrients are dissolved in the water after mixing it up. You know the PPM of the water you're adding the nutrients to. You measure the PPM after the adding the nutes, and you know how much of the nutrients you've added. It is a way of measuring nutes just like a big syringe, or other liquid volume measuring container. It is a more accurate way of measuring how much nutrients are in the reservoir or the water mixed with nutrients you are going to feed your plants in soil than only measuring the volume of nutrients in a syringe or measuring glass or whatever.

The PPM tells you nothing about the ratio of the different nutrients and stuff in the water/feed mix. It is just an indicator of the strength of the mix. The ratio of the different nutrients is only known from how much of each thing is in the nutrients you are mixing with the water, and knowing what is in your water already. You can do the math and figure it out somewhat accurately if you are mathematically inclined. There are already nutrients and often added fluoride for dental health (or bad things like chlorine, lead, tritium, perchlorate, etc) in the water before you add nutes.

If you measure the PPM of your tap water five times in a week there will be variation each time - hopefully not big variations. The only way to know what is in the water coming out of your tap is by looking at the municipal water report for your neighborhood in a town or urban area. The city I live in has reports for twenty or so different zones and they are all different. Also, the reports are based on several samples that change from day to day and are averaged. The water out of your tap is not the same every time. Ever poured yourself a glass of water from the tap and it tastes better or like crap compared to what you typically get? The PPM's are different than they usually are. If you have a well, you can get your water tested by the county, the cooperative extension service. etc.

Things become increasingly complicated from here… pH and PPM are separate measurements of different things. However, some of the things other than hydrogen and oxygen in your water or water/ nutrient mix are really good at taking the hydrogen that is not attached to oxygen to make water and making that hydrogen a part of itself. Since pH is the measure of hydrogen that is not attached to anything in your water or water nutrient mix, the things you add to the water can change the pH. The same is true of just plain well or tap water. What is in the water changes the pH of the water because some of those things are pulling hydrogen not attached to anything They make the formerly free and separate hydrogen part of them. This changes the pH. You are measuring two separate things, but those two separate things affect each other….

The other thing that meters read is EC. That is the abbreviation for electrical conductivity. Different things conduct electricity differently. You cannot make a wire for a lamp in your house out of string. Copper is a great electrical conductor, and you can make wire for a lamp out of it. The EC gives you clues about what is in your water or water/nutrient mix, but it does not tell you exactly what is in your mix any more than pH or PPM.

Combined, pH, PPM, EC, and the analysis of the nutrients you feed your plant can give you a lot of information about what is in the mix, but they don’t tell you exactly.

I am not a botanist, but I know quite a bit about human metabolism. Many of the principals of human metabolism and plant metabolism are the same, but there are significant differences, too. In both cases, for example, magnesium is needed every time ATP is added or moved around to a different position in a molecule. That is not important to know - just an example. Since I started growing cannabis I’ve become more interested in plant metabolism and I have enough background in biochemical mechanisms to increase my knowledge of plant metabolism quicker than most folks new to the subject.

It is quite complicated! Nobody understands all the metabolic intricacies entirely, but we learn more all the time. Cannabis metabolism is difficult to study because of the current prohibition against this wonderful and beneficial plant.

In the last two years LED lighting has taken off. It is a big trend. The other thing that, in my opinion, is going to explode as a trend are complete soils tailored to growing the plant like Doc’s kit, supersoil, etc. The reason is that many of the bacteria in the soil help regulate pH, nutrient availability, etc. Those bacteria (and fungi, too,) break down organic matter and turn it into plant food. The trend is feeding the bacteria instead of the plant. They do the work so you don’t have to – sort of like the scrubbing bubbles in a popular basin, tub and tile cleaner.

More and more companies are going to devote research money to helping soil growers make these soils. In the same way that the market for HPS and MH lighting is being eroded by increasingly effective and energy efficient LED lights, soil amending is going to erode the market for the huge array of liquid nutrient kits on the market. The days of trying to decide how much of this bottle and that bottle to add to the water we feed our plants are numbered. So are the days of scrutinizing our plants for problems and trying to decide what we need to do to fix the issue. The stress level goes WAY down with a nice soil medium.

Before dropping cash on more watts of light, soil growers are increasingly seeing the value of spending money on complete bioactive growing mediums. The gap between yield and quality between soil and a well maintained hydro system is closing quickly, largely due to the rapidly expanding experimentation with complete soils geared towards growing our favorite plant: growing mediums that take the guesswork out of how much to feed and when, and trying to diagnose deficiencies, toxicities, and lockouts.

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