First of all, we need to have a basic understanding of pH, and how pH levels effect plants grown in a hydroponic system.

PH is a measurement of how acidic or alkaline the nutrient solution is, and runs on a scale of 1 to 14 with neutral (pure water) being 7.

The pH level affects the availability of nutrients within the solution, and therefore how easily the plants can access these nutrients. PH is the most important factor to be controlled with nutrient solutions and poor pH management can produce weak plants with minimal yields.

When grown in soil, different plants will grow best at different pH levels. However, most plants grown hydroponically prefer a slightly acidic level of around pH 6 (in a range of pH 5 — pH 7).



Individual plants will have their own preferences within this range.

If the nutrient solution falls outside of this range, the nutrients the plant needs to maintain healthy growth will either precipitate from the solution or become locked-out (page 15) and the plants growth will suffer.

The chart below shows how much of each of the major elements are available at different pH levels. It is only at a pH level of around pH 6 that there is significant availability of all the nutrients.



It should be noted that the pH scale is logarithmic. This means that every point on the scale represents a tenfold increase in either acidity or alkalinity. This is why a small change in the pH level can have a major impact on the nutrient availability in the solution.

PH 7= NEUTRAL (PURE WATER).
PH 6=10 TIMES AS ACIDIC AS PH 7.
PH 5=100 TIMES AS ACIDIC AS PH 7.
PH 4=1,000 TIMES AS ACIDIC AS PH 7.
PH 3 = 10,000 TIMES AS ACIDIC AS PH 7.
Etc,etc.

The nearer the pH is to 6.0 the easier it is for a plant to feed, the easier it is to feed the more it will use and the more it uses the bigger and better it will get!