hydroponics.howFIELD GUIDES 02
FIELD GUIDE / Aerated deep water culture

Source water and alkalinity

Read a laboratory report, distinguish equivalent units from elemental nutrients and prepare water deliberately.

6 min + guided practiceWorked quantities & explicit assumptionsReview status ↗
3D FIELD MODEL / DWC–01
Aerated deep water culture: The root bath → Separate air delivery → Root access. Suspended roots in an aerated nutrient bath; no circulation pump is required in this single-vessel example.1 / RESERVOIRThe root bath2 / AIRSeparate air delivery3 / ROOTSRoot accessSeparate air supply; single nutrient bath.

Loading the interactive model. The complete lesson is available below.

All components and instructions are available without 3D. Illustrative geometry and flow. Not a simulation.
AFTER THIS CHAPTER
  • Read elemental and equivalent water-test units.
  • Select treatment for an identified problem.
  • Prepare documented makeup water.

01 / The water is already an ingredient

Source water can contain useful calcium and magnesium, unwanted sodium or chloride, alkalinity and disinfectants. Measure or analyze before selecting a fertilizer program. Clear water is not necessarily low in dissolved salts.

Request a report appropriate to irrigation or aquaculture, including pH, EC, alkalinity, hardness and relevant individual ions. Keep the sample date, source and treatment history. A municipal report describes the supply, while an actual sample can reveal conditions after your storage or treatment.

Reading: Interpreting Irrigation Water Tests ↗ · Hydroponic Nutrient Solutions (G6984) ↗

02 / Decode the reporting basis

Alkalinity and hardness commonly use mg/L as CaCO₃, an equivalent reporting convention. That value is not the mass of elemental calcium dissolved in the sample. Calcium in mg/L Ca can be entered as a source-water nutrient contribution; total hardness cannot.

Nitrogen compounds also have reporting bases: nitrate-N measures only nitrogen mass, while nitrate measures the whole NO₃ ion. The approximate conversion is NO₃ = nitrate-N × 62/14, or 4.43. Nitrite uses 46/14, or 3.29. Keep the original basis and convert explicitly when comparing sources.

Report labelMeaningDo not substitute for
Ca, mg/LElemental calcium concentrationHardness as CaCO₃.
Alkalinity, mg/L as CaCO₃Acid-neutralizing capacity on an equivalent basispH or elemental calcium.
NO₃-N, mg/LNitrogen mass within nitrateNO₃ mg/L without conversion.
EC, mS/cmConductivity of the ion mixtureA complete nutrient analysis.

03 / Match treatment to the problem

Chlorine and chloramine require appropriate removal before sensitive fish or microbial systems. Standing water is not a reliable generic method for chloramine. Verify the treatment against the disinfectant actually used and test the result.

Reverse osmosis can reduce dissolved constituents but creates a separate reject stream and changes alkalinity and nutrient contributions. Softening is a different process and can exchange calcium/magnesium for sodium or other ions, depending on the unit. Do not assume softened household water is equivalent to low-salt RO water.

Reading: Important Water Quality Parameters in Aquaponics Systems (CR680) ↗ · Interpreting Irrigation Water Tests ↗

04 / Establish a reproducible water batch

Prepare makeup water separately when fish or sensitive roots would be affected by temperature or chemistry differences. Record source, treatment, volume, temperature, EC, pH and relevant disinfectant results.

For pH adjustment, use the actual chemical label and a controlled small-volume trial informed by alkalinity. A universal millilitres-per-litre acid instruction cannot be derived from starting pH alone. Keep the treated-water contribution in nutrient calculations.

  1. Collect a representative sample in the laboratory’s prescribed container.
  2. Read every result with its unit and reporting basis.
  3. Identify the specific problem and select a treatment designed for it.
  4. Verify treated water rather than assuming the equipment worked.
  5. Recheck after source, seasonal or treatment changes.
ILLUSTRATED SYSTEM INVENTORY

Parts & buying criteria

Showing aerated deep water culture. Quantities describe the teaching model. Specify real working volume, support, fittings and instruments for your installation.

01Nutrient reservoir1 · illustrated quantity+

Stores the measured nutrient solution beneath or beside the growing area.

Inspect: Compare the surface with the pump intake or lower roots; freeboard is deliberate.

Maintain: Record level before refilling, keep light out and verify temperature, EC and pH.

BUYING CRITERIA

Opaque, cleanable, intended-use container with volume marks and service access.

Supplier links can be added by the publisher. The criteria stand independently.
02Lid & root support1 · illustrated quantity+

Holds the plant above the chamber or reservoir without pinching its crown.

Inspect: Separate the cover and inspect the basket or collar opening.

Maintain: Check fit as plants grow and keep unused openings covered.

BUYING CRITERIA

Rigid compatible support with removable, correctly fitted baskets or collars.

Supplier links can be added by the publisher. The criteria stand independently.
03Air pump & diffuser1 · illustrated quantity+

Delivers air below the water surface in this aerated DWC example.

Inspect: Trace the thin line from the dry pump to the diffuser. Bubbles are illustrative.

Maintain: Check actual delivery and dissolved oxygen; preserve backup air and prevent back-siphoning.

BUYING CRITERIA

Rated output at the installed depth and diffuser resistance; accessible replaceable parts.

Supplier links can be added by the publisher. The criteria stand independently.
SOURCES & EDITORIAL STATUS

Evidence beside the lesson.

Source checks: September 2026. The geometry, inspection exercises and worksheets are original teaching material. The named organizations have not endorsed or reviewed this site.

Independent specialist review is pending.

Published recipe rates and planning ranges retain their source context. Calculator equations are accounting tools; they do not predict uptake, yield, toxicity or safe stocking. Model dimensions, water speeds, roots and fish counts are illustrative. Verify species, crop, source water and product labels for a real system.

  1. Penn State ExtensionInterpreting Irrigation Water Tests ↗

    Distinguishing alkalinity, pH, salts and source-water problems.

  2. University of Missouri ExtensionHydroponic Nutrient Solutions (G6984) ↗

    Solution preparation, elemental nutrition and measurement.

  3. New Mexico State University ExtensionImportant Water Quality Parameters in Aquaponics Systems (CR680) ↗

    Fish-system water chemistry, oxygen, temperature and nitrification.

CONTINUE LEARNING

The next useful connections.

Nutrients & mixing

Nutrient mixing: from grams to elemental ppm

Scale two documented fertilizer examples, read the bag analysis and calculate what actually enters the final solution.

Interactive tool · 6 min + guided practice →Nutrients & mixing

EC, pH and the two “ppm” scales

Calibrate your instruments, record unambiguous units and interpret concentration without pretending EC is a nutrient analysis.

Interactive tool · 6 min + guided practice →

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