Potential of Hydrogen

pH

Description
Used to specify the acidity or basicity of aqueous solutions. Acidic solutions (solutions with higher concentrations of hydrogen (H+) cations) are measured to have lower pH values than basic or alkaline solutions.
See Also
4.5–9 pH Test Strips
GH pH Up
GH pH Down
Liquid Culture Hydroponic System Operation
Precise Management of Hydroponic Nutrient Solution pH: The Effects of Minor pH Changes and MES Buffer Molarity on Lettuce Physiological Properties
Last Updated
2026-06-01
Reading Time
2 minute(s)

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4.5–9 pH Test Strips
GH pH Up
GH pH Down
Liquid Culture Hydroponic System Operation
Precise Management of Hydroponic Nutrient Solution pH: The Effects of Minor pH Changes and MES Buffer Molarity on Lettuce Physiological Properties

The pH of the hydroponics reservoir should be between 5.5 and 6.5.

Optimum Water pH

Don't add the pH adjusting solution straight to the reservoir or you may shock the plant roots.

Add it to a gallon jug and let dilute for 5 minutes before slowing pouring the solution into your reservoir.

Adjusting pH Levels

pH should always be checked after getting the EC into the optimum range.1

pH and EC

Generally, fertilizer with Ammoniacal Nitrogen will tend to decrease pH, and fertilizer with Nitrate Nitrogen will tend to increase pH.2

Fertilizer on pH

pH Meter

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Zeroing a pH Meter

There's a bottle of pH 7 solution.

Cleaning a pH Meter

Rinse with water. No soap is necessary.

If the pH is High (Lowering pH)
If the pH is Low (Raising pH)

  1. Electrical Conductivity and pH Guide for Hydroponics ↩

  2. Mattson, N., & Lieth, J. H. (2019). Liquid Culture Hydroponic System Operation. In Soilless Culture (pp. 567–585). Elsevier. https://doi.org/10.1016/B978-0-444-63696-6.00012-8 ↩