What is a pH Meter ? A pH meter is an electronic device used for measuring the pH of  your water. A typical pH meter consists of a special measuring probe connected to an electronic meter that measures and displays the pH reading.
You’ll often read the recommendation to check the pH of your water and soil, but what does that really mean?
Plant roots absorb mineral nutrients such as nitrogen and iron when they are dissolved in water. If the nutrient solution (the mixture of water and nutrients) is too acid or alkaline ( too high or too low pH ), some nutrients won’t dissolve easily, so they won’t be available for uptake by your plants roots.
Most nutrients that plants need can dissolve easily when the pH of the soil solution ranges from 6.0 to 6.5.
In Hydroponics the range is 5.5 to 6.0.
Below pH 6.0, some nutrients, such as nitrogen, phosphorus, and potassium, are less available. When pH exceeds 7.5, iron, manganese, and phosphorus are less available.
We recommend testing the pH of your water after you have added your nutrients as some nutrients may bring the pH up or down !!