Warm solution holds less dissolved oxygen, and it encourages root rot and algae. Summer heat is one of the most common reasons a healthy hydroponic system starts to struggle.
Why heat causes trouble
As water warms, it holds less oxygen. Roots need oxygen to breathe, so when it runs short they weaken and can start to rot. Warm conditions also help algae and some root pathogens grow faster. The problem often builds slowly, so check the system during hot spells.
Signs the solution is too warm
- Roots that look brown, soft or slimy.
- Wilting even when the reservoir is full.
- Algae growing quickly on the reservoir walls.
- A sour or unpleasant smell from the solution.
What to do
Move the reservoir out of direct sun, and keep it away from heat sources such as grow lights, heaters and sunny windows. Cover the reservoir to cut down on light and evaporation. Check that the air pump is running and that the air stone is not blocked. In very hot weather, you can replace some solution with cooler, fresh water and recheck the pH, because the balance can shift.
Prevention
Plan where the system will sit before summer arrives. Light-coloured or shaded containers help, and so does good airflow around the reservoir. Keep records of the water temperature if you can, so you notice trends early.
Keep learning
Related guide: Common Hydroponic Problems and Fixes. You can also read the guides hub or the FAQ.