Hydroponic Troubleshooting Guide
Fix common hydroponic problems. Diagnose and solve nutrient deficiencies, pH issues, root rot, and algae in UK growing systems.
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Take Our QuizPlants communicate through their leaves. Learning to read these signals transforms troubleshooting from guesswork into diagnosis.
Yellow Leaves:
Older leaves yellowing: Usually nitrogen deficiency or natural aging. Feed more if it's spreading upward.
Younger leaves yellowing with green veins: Iron deficiency, typically caused by high pH. Check and lower pH.
All leaves pale: General nutrient deficiency or light issue. Check EC and light levels.
Root Problems:
Brown, slimy roots: Root rot. Caused by insufficient oxygen, warm water, or pathogens. Solutions: increase aeration, lower water temperature (below 20C ideal), add beneficial bacteria.
Brown but firm roots: Nutrient staining. Normal with some fertilisers. Only worry about slimy roots.
Algae: Green growth on surfaces or in solution. Caused by light reaching the nutrient solution. Not directly harmful but competes for nutrients and can clog systems.
Prevention: Use opaque containers, cover exposed solution, maintain cleanliness.
pH Fluctuations:
pH rising: Usually means plants are taking up more nutrients than the solution can buffer. Time for a change.
pH dropping: Less common. May indicate bacterial activity or contaminated solution.
Stable pH but plants struggling: Check EC. pH can be perfect while nutrients are depleted.
Wilting:
With wet roots: Overwatering (in media-based systems) or root rot. Check roots.
With dry roots: Underwatering, pump failure, or reservoir empty.
In bright light only: Heat stress. Increase ventilation or shade.
Slow Growth:
Check light first. Insufficient light is the most common cause.
Then check temperature. Growth slows below 15C and above 30C.
Then check nutrients. Low EC limits growth potential.
Pests: Fungus gnats love wet growing media. Let the top dry between waterings or cover with sand.
Aphids appear seemingly from nowhere. Inspect new plants. Remove by hand or use insecticidal soap.
Our Advice: When problems appear, check the basics first: pH, EC, light, temperature. The cause is usually mundane, not exotic.
Change one thing at a time. Wait 3-5 days to see results. Overcorrection causes more problems than it solves.
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Start the QuizFrequently Asked Questions
Why are my hydroponic plants turning yellow?
Yellowing usually means nitrogen deficiency or pH lockout. Check pH first (should be 5.5-6.5). If pH is fine, increase nutrients by 20%. Lower leaves yellowing is normal as plants mature, but new growth yellowing needs addressing.
How do I prevent root rot in hydroponics?
Keep water temperature below 22°C, ensure adequate oxygen (air stones for DWC), keep light out of reservoirs (algae creates problems), and use beneficial bacteria like Hydroguard. Brown, slimy roots mean rot - healthy roots are white and firm.
Why is algae growing in my hydroponic system?
Light + nutrients = algae. Block all light from reservoirs and channels with opaque containers or black tape. Algae competes with plants for nutrients and reduces oxygen. Prevention is easier than cure.
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