Reverse osmosis (RO) is a water purification process that forces water through a semi-permeable membrane under pressure, removing up to 95β99% of dissolved salts, minerals, chlorine, chloramines, and other contaminants. In hydroponics, RO water is used as a clean baseline β essentially mineral-free water with near-zero EC β allowing growers to build a precisely controlled nutrient solution from scratch without interference from unpredictable tap water chemistry.
Key Facts
- Produces near-pure water with EC close to 0.0 mS/cm and pH typically 6.0β7.0
- Removes chlorine, chloramines, heavy metals, and dissolved salts from tap water
- RO water has zero buffering capacity β pH swings are more sudden and harder to stabilise
- Cal-Mag supplementation is essential when using RO water (no baseline Ca/Mg)
- RO systems waste 3β4 litres of water for every 1 litre of purified water produced
- Essential for growers in areas with hard water (EC above 0.4) or high sodium content