ConductScienceConductScience

Conductivity & Dosing Runtime Planner

Plan conductivity adjustments for aquatic systems. Calculate salt stock dosing volume, pump runtime, and stepwise dosing schedule with unit conversion (µS/cm, mS/cm, ppt).

ZebrafishWater QualityDosingClient-Side
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Try it out

Load example Conductivity Dosing data to see the full workflow

Configuration

Default: 10,000 mg/L (10 g/L NaCl stock)

Use facility calibration factor
  • Planning salt stock additions to raise system conductivity after water changes
  • Calculating pump runtime for automated dosing systems
  • Creating stepwise dosing schedules for gradual conductivity adjustment
  • Converting between conductivity units (µS/cm, mS/cm, ppt) for different meters

Don't use for

  • For decreasing conductivity — use partial water changes with RO/DI water instead
  • As a substitute for direct conductivity measurement — always verify with a calibrated meter
  • For marine or brackish systems — this tool is calibrated for freshwater zebrafish ranges

Conductivity and Salinity in Zebrafish Systems

Conductivity is the standard measure of dissolved ion content in recirculating aquatic systems. For zebrafish (*Danio rerio*), which are freshwater teleosts, maintaining appropriate ionic strength is essential for osmoregulation, gill health, and reproductive success.

Key ranges (µS/cm): - <200: Ion-poor — osmotic stress, poor egg quality - 300–500: Acceptable low range - 500–800: Optimal for most facilities (target ~700 µS/cm) - 800–1500: Acceptable high range - >1500: Risk of gill irritation and impaired development

Most facilities use a blend of salts (NaCl, CaCl₂, MgSO₄, NaHCO₃) or commercial preparations (e.g., Instant Ocean at 0.3–0.5 g/L) to achieve target conductivity while also providing appropriate hardness and buffering.

Dosing Best Practices

Adjusting conductivity should be done gradually to avoid osmotic shock:

Stepwise dosing protocol: 1. Measure current conductivity with a calibrated meter 2. Calculate the total stock volume needed (this calculator does this) 3. Divide into 3–5 increments 4. Add each increment, wait 5 minutes for mixing, then re-measure 5. Stop when target is reached — do not rely solely on calculated volumes
Common pitfalls: - Adding stock directly to the sump without mixing — creates local hot spots - Not accounting for biofilter salt consumption (bacteria consume some ions) - Using table salt with iodine or anti-caking agents — use aquarium-grade or reagent-grade NaCl - Assuming conductivity is stable — it drifts due to evaporation (increases) and water changes (decreases)

Frequently Asked Questions

Next Steps

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