Reference No.: 62
Title: pH Control in Hydroponics
Author: Bret H (onestopgrowshop.co.uk)
Primary Topic: Farming
Year: 2013
URL: https://www.onestopgrowshop.co.uk/blogs/news/ph-control-in-hydroponics
My notes on this reference #
Understanding pH in Hydroponics
- pH measures acidity or alkalinity; below 7 is acidic, above 7 is alkaline, and 7 is neutral.
- Nutrient availability varies with pH; ideal range for hydroponics is 5.5–5.8.
Nutrient Availability and Growth
- Plants require all nutrients (macro, secondary, micro) for optimal growth.
- Liebig’s Law of the Minimum: Growth is limited by the scarcest nutrient.
- Maintaining pH at 5.5–5.8 ensures all nutrients are accessible.
pH Drift
- pH of nutrient solutions naturally rises after adjustment, influenced by:
- Non-neutral grow mediums like Hydroton.
- Impurities in non-distilled water binding with pH Down.
- Ingredients in nutrients causing drift; some contain pH buffers.
- Stronger nutrient solutions causing faster drift during peak growth.
- pH stabilizes later in the week after a solution change but requires daily checks.
pH Measurement and Adjustment
- Tools needed: pH pen, phosphoric acid (pH Down), pipette.
- Adjustment steps:
- Measure pH.
- Add pH Down gradually, stirring and rechecking until pH is 5.5–5.8.
- Avoid overshooting to prevent using pH Up unnecessarily.
- Recheck pH daily for optimal plant growth.
Maintaining Your pH Meter
- Calibrate regularly using pH 4 and/or pH 7 calibration fluids.
- Clean the glass sensor after each use to prevent salt contamination.
- Use pH probe cleaning solution monthly for accuracy.
- Replace meters every 6–12 months for reliability.
Key Principle
- Liebig’s Law emphasizes that deficiency in any single nutrient restricts plant growth, highlighting the importance of proper pH management.