Water & Reservoir
What is the best water temperature for hydroponic cannabis?
The answer is: 67°F
An ideal working range is about 67 to 68°F.
Why
Target a reservoir temperature of 67°F, with about 65 to 68°F as a practical working range. As water warms, its maximum dissolved-oxygen capacity falls, which matters because hydroponic roots live in that water continuously. Warm water by itself does not create root rot; a pathogen still has to be present. But warmer conditions reduce the oxygen ceiling and can favor aggressive Pythium species. A chiller controls temperature and aeration supplies oxygen. Those are separate jobs, and you want both working well.
What to remember
- Target 67°F reservoir temperature.
- About 65 to 68°F is a practical working range.
- Warmer water has a lower dissolved-oxygen ceiling.
- Warm water alone does not cause root rot; a pathogen must be present.
- The chiller controls temperature. Aeration supplies oxygen.
Keep growing