pH is the measure of Acidity and Alkalinity of a solution. pH is measured on a scale of 1-14 with 7 being neutral, Acids have a pH lower than 7 and Alkalines have a pH higher than 7.
The level of acidity in your homemade hydroponic system is very important. Each of the essential elements making up the hydroponic nutrient are released into the nutrient solution at a specific pH range.
Plants are only able to absorb nutrients that have been released into the nutrient solution.
The optimal pH range of hydroponic nutrient solution is 5.8-6.3
If the pH goes below 5.5 then the concentration levels of available micro-nutrients Iron, Manganese, Boron, Copper and Zinc will increase and can become toxic to the plant. The increase in micro-nutrients will also decrease the availability of Calcium and Magnesium.
The affect of the change is nutrients is much more important in hydroponics as this is a closed system with no soil to buffer the nutrients.
There are several ways of testing the pH of your nutrient solution. These are listed from cheapest to most expensive.
Litmus Paper are strips of paper that have been impregnated with a pH sensitive dye. The dye changes colour when dipped into the nutrient solution. The paper is then compared to a colour chart to determine the pH level of the solution being checked. Litmus paper comes in pH ranges, so ensure that you purchase one the will cover pH 5 to pH 8.
Liquid pH Test Kits
Liquid pH Test Kits work by adding a few drops of a pH sensitive dye to a small amount of the nutrient solution and then comparing the color of the resulting liquid with a color chart.
pH Meters are an electrical monitor device that will display the pH level of your nutrient solution in seconds. There are a huge range of pH Meters, ranging from inexpensive pen-like devices to expensive commercial models.
pH Meters need to be looked after properly and calibrated regularly. Most pH Meters need to have the actual sensor to be moist at all times and to be stored in a buffer solution.
pH Buffer solutions are available at your local hydroponic store. These solutions will raise or lower the pH of your nutrient solution to the desired level.
With small a small nutrient reservoir the amount of buffer solution will be minimal, so take care or you could over buffer your nutrient solution.