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Cannaversity .: Cannabis Cultivation .: Nutrients & Mediums .: What is pH and why is it important?

What is pH and why is it important?

pH Explained

pH is a measure of the degree of the acidity or the alkalinity of a given solution as measured on the pH scale of  0 to 14. The midpoint of 7.0 on the pH scale represents  a "neutral" solution which is neither acid nor alkaline based. Numbers below 7.0 indicate an acidic base and numbers greater  than 7.0 indicate alkalinity.
It is important to understand that pH is a measurement of intensity, to use an everyday comparison

" pH indicates the intensity of alkalinity in the same way temperature tells how hot something is - but not how much heat the substance carries."

The pH scale is logarithmic which means that moving on (unit either way on the pH scale results in a 10 fold increase in the degree of alkalinity or acidity).

Some typical pH values are included in the following table






hydrochloric, sulfuric, nitric acids


phosphoric, sulfamic acids



citrus fruit












caustic soda, floor strippers

As a general rule of thumb, cleaning performance on typical oily soils is enhanced with an increase in pH. Some soils, for example hard water deposits, are best removed with acids.

Products at the two extremes (less than pH 1 or greater than pH 13) are extremely oppressive and corrosive. Examples include sulphuric and hydrochloric acid on the acid end, and caustic soda on the alkaline end. Use solutions of phosphoric or sulfamic acid cleaners, typically in the pH range of slightly less than 2, may be described as "safe" acids comparison to the stronger acids. Of course, necessary safety precautions (eye and hand protection) as noted on the Material Safety Data Sheet should always be followed.

As an illustration of their non-aggressive behaviour in comparison to stronger acids, products containing sulfamic or phosphoric acid were found to result in no chemical attack on nylon carpets. On the other hand, a hydrochloric or powder acid-based product would basically dissolve the fibres.

Other than the two pH extremes, the pH scale becomes secondary to the inherent properties of the specific chemical in terms of corrosiveness. As an example, the pH of carbonated cola soda (which contains phosphoric acid) is in the 2.5 range. A concentrated (35%) hydrogen peroxide solution has a pH of approximately 3.5. Carbonated cola soda may be slightly irritating to the eyes, causing no permanent damage. However, a 35% hydrogen peroxide solution will cause chemical burns to the skin or mucous membranes. Thus, it is not the pH factor alone that causes corrosion of products to surfaces.

Relative pH info for Growers

  Now you have a complete understanding of what pH represents it's time to get into a bit more info that relates to growers. As shown above pH is represented by a numerical scale that expresses the acidity or alkalinity of a solution (in our case the water in our reservoir).
Marijuana thrives in slightly acidic mediums. Soil and soil less mixes should aim for pH of 6-6.4  and hydro growers should go slightly lower which helps prevent pythium and other root rots 5.5-5.7 is an ideal starting point allowing it to fluctuate up to but not over 6.1. The reason this information about pH is so important is because of the availability of different minerals needed by the plant to grow changes at different pH levels. This is best demonstrated by looking at the chart bellow that I found on the Forums which outlines the appropriate pH range for growers and what minerals are available at the different pH levels in that range.



Tutorial written by Pure for




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