Record what changed
Take a photo of the whole plant, a young leaf and the damaged area. Note when you first saw the change and what happened before it: topping up, replacing the solution, fitting a new light or moving a seedling. Record whether one plant or the whole reservoir is affected. This helps separate a shared system problem from damage to one plant.
If a plant is rapidly losing firmness, check water access and equipment immediately. You do not need several days of photographs before doing that. For gradual yellowing, collect readings before adding another product.
Check water delivery and roots
See whether the roots reach the solution. Check that the pump actually delivers water, the tubing is open and the DWC diffuser works. A humming air pump does not prove that air reaches the reservoir. In a substrate system, check moisture inside the plug and make sure drainage is clear.
Handle roots gently. Fertilizer and growing media can stain them, so a brown patch alone does not establish an infection. Slime, an unpleasant smell, tissue breakdown and wilting together call for a closer check of the solution and sanitation. A photograph cannot reliably identify a pathogen.
Confirm readings before adjusting the tank
Record water level, solution temperature, pH and EC. Check meters against appropriate standards if readings change sharply or do not fit the care history. Never pour used calibration solution back into its bottle.
In DWC, compare EC at a known working volume. A shrinking reservoir can become more concentrated without extra fertilizer. In Kratky, preserve the air gap: filling to the original level can submerge roots that developed above the water.
Use symptoms to choose a check
| Observation | Possible causes | First check |
|---|---|---|
| Whole plant wilts | Interrupted water delivery, heat, root damage, concentrated salts | Water delivery, temperature, roots and EC |
| Older leaves turn yellow | Age, shading or a nutrient problem | New growth, solution history and pH |
| Young leaves become pale | Poor nutrient availability or root function | pH, roots and complete fertilizer composition |
| Leaf edges dry out | Salt stress, climate or local nutrient problems | EC after checking volume, heat and airflow |
| Stems stretch | Insufficient light or crowded plants | Light at leaf level and plant spacing |
Deficiencies and root problems can look similar. Adding a single element based on leaf colour changes the solution and can make the original cause harder to identify. Check conditions that affect uptake of the whole mix first.
Make a change supported by a check
Fix the fault you found: restore water delivery, straighten a pinched tube or reduce reservoir overheating. If you have lost the recipe and cannot establish the solution composition, prepare a fresh complete mix for the crop and stage. Record why you replaced it.
Log the time and readings after the action. If deterioration continues rapidly, check water and roots again without delaying action to preserve the experiment. If disease is suspected, separate the plant where the system allows it and keep solution and tools away from healthy systems.
Judge recovery by new growth
Old dead tissue usually remains visible after conditions improve. Watch firmness, new roots and new leaves. Photos taken from the same distance are more useful than a general impression that the plant looks greener.
If the problem returns straight after a solution change, check what stayed the same: source water, meters, lighting, temperature and equipment. Another dose of fertilizer can repeat the same mistake.