Cloudy stock solution is a reason to pause and identify the material before it reaches the crop. It may reflect incompatible fertilizer salts, incomplete dissolution, the source water or insoluble product additives. A finer irrigation filter can catch some solids, but it cannot put precipitated nutrients back into the intended recipe.
Keep the affected batch separate while the grower and fertilizer supplier investigate. Preserve the product labels, mixing record and a correctly labeled sample. Do not add acid, bleach or another product to “clear” an unknown mixture.
Why A and B tanks are separate
Some materials that coexist in a dilute crop solution react when concentrated together. UF/IFAS greenhouse fertilizer guidance identifies calcium phosphate and calcium sulfate as examples of precipitates arising from incompatible concentrated ingredients. Separate stocks allow compatible materials to be kept apart until dilution in the designed system.
The letters on the tank are not a chemistry specification. One supplier’s “A” may not mean the same formulation as another’s. Label every tank with its actual approved contents, concentration and revision date. A replacement fertilizer product requires a compatibility check even when its headline nutrient numbers look familiar.
Locate where the first change appears
Take observations at the raw water, freshly prepared stock, settled stock and final diluted solution. Note elapsed time and temperature. Use the supplier’s sampling instructions; opening a pressurized line is not a sampling method.
| Where the problem appears | Questions for the investigation |
|---|---|
| One ingredient does not dissolve in a clean vessel | Is the product suitable for the intended stock concentration and water temperature? Is the specified mixing method being followed? |
| Cloudiness begins when another ingredient is added | Are the concentrated ingredients compatible? Was the approved tank assignment followed? |
| Stock is clear but mixed output changes | What are the dilution, mixing sequence and incoming water conditions at that point? |
| Deposits appear only after storage | Did the stock cool, evaporate or become contaminated? What does the product supplier say about storage? |
These are investigation branches, not chemical diagnoses. Similar-looking deposits can have different origins. A photograph cannot establish whether a white residue is a carbonate, sulfate or an inert additive.
Reconstruct the batch before adjusting equipment
Ask the operator to reconstruct what actually went into the tank: source-water batch, ingredient order, masses, final volume, water temperature and any remaining solution from the previous batch. Check whether a scoop or hose was shared between concentrates. Confirm that the written recipe and the tank label show the same revision.
A practical record has a field for each input and a place for a second check when the operation requires it. Leave a missing value marked unknown. Filling the gap from memory creates an apparently precise record that may lead the investigation in the wrong direction.
Penn State’s nutrient-solution guide also explains the role of separate concentrated stocks. Use the formulation-specific instructions, not a generic two-tank diagram, to determine which products belong together.
Do not let a mechanical repair become a dosing change
Cleaning a strainer may restore flow while leaving the remaining stock chemically different from the intended mix. Increasing the injector setting to compensate can then overfeed components that stayed dissolved. Before restarting, have the supplier or crop adviser decide whether the stock can be used and what solution analysis is needed.
Inspect affected equipment according to its maintenance instructions. Define disposal of residue and rinse water through the site’s approved process. Chemical cleaning, acid dosing and any treatment of a blocked line require the product-specific procedure and competent staff.
After resolving the stock problem, check the injector’s actual dosing ratio before judging the delivered feed. Correcting a mixing error and correcting a ratio error are different jobs.
Design out the recurring handling error
If the same problem keeps returning, review the workstation: dedicated utensils, unmistakable tank labels, clean access to the fill marks, covered storage and enough room to inspect suction lines. Ask CFGET to coordinate these needs with the fertigation supplier when planning the service area.
Before preparing the next batch, verify the recipe revision, compatibility, product solubility and final-volume method. Then retain one complete batch record and a delivered-solution check. That evidence is more useful than choosing a stronger filter from the appearance of the sediment.
