The pH level of a liquid solution tells us how acidic or alkaline it is on a scale from 0 to 14, with 7.0 indicating a pH-neutral solution. From this neutral midpoint, the solution becomes increasingly acidic as the pH approaches zero and increasingly alkaline as the pH approaches 14. Pure water is pH neutral.
When you look at the chemistry behind pH, as you probably know, water molecules consist of two hydrogen atoms and one oxygen atom (H2O). But when a compound dissolves in water and produces free ions (atoms or molecules with an electrical charge), it can cause some of the water molecules to split apart, creating positively charged ions (H+) and negative charged hydroxide ions (OH-).
The pH of a solution indicates the concentration of free hydrogen ions it contains. Pure water has equal concentrations of H+ and OH-, while acidic solutions have higher concentrations of H+ than OH- and alkaline solutions have the reverse. These characteristics at the molecular level are responsible for the sour and corrosive properties of acid solutions and the bitter, slippery nature of alkaline solutions.
A pH value is a scale measurement, meaning that each whole number represents a tenfold difference in the concentration of hydrogen ions, and therefore, a tenfold difference in the strength of the acidity or alkalinity.
In soil based planting, plant roots absorb nutrients dissolved in water which originate from organic and inorganic compounds in the soil. Microorganisms and organic matter play a role in the formation and fertility of the soil, while interactions of minerals and water fluctuations in pH levels naturally control soil’s pH. Plants that grow in these soils have evolved and adapted themselves to take advantage of these controlled soil pH levels. Hydroponic growers are solely responsible for recreating the ideal environments that encourage plant roots to absorb vital nutrients.
Whichever type of hydroponic system you are using, the goal is to always deliver water and nutrients to the roots of plants via a water-based nutrient solution. And while it’s crucial that you deliver a consistent supply of the nutrients that are appropriate for the types of plants you are growing, it’s also vitally important that you provide the proper pH levels for nutrient uptake.
Monitoring and adjusting pH in hydroponics ensures the nutrient availability of your solution. Subsequently, if your nutrient solution doesn’t have the correct pH, you risk starving your plants – even though you are providing them with plenty of nutrients.