Skip to content

Reservoir Size Calculator

Calculate hydroponic reservoir volume from plant count, system type, and refill interval. Size nutrient tanks for DWC, NFT, and drip systems.

Use this result well

Inputs that matter
Plant Count, Plant Size, System Type
Output to expect
Reservoir Size Calculator
  • Check the units and required inputs before comparing results.
  • Keep the assumptions with a copied result so you can reproduce the calculation later.
Was this tool helpful?

Related Tools

Tools you might need next

Reviewed Nutrient Stock-Dilution Record Reconciliation

Reproduce one source-owned analyte stock-dose record from explicit mg/L concentrations and final volume, then compare completed and independent doses.

Recommended next stepHydroponics
Grow Room Calculator

Plan indoor grow room dimensions, plant capacity, lighting, and ventilation CFM requirements for hydroponic cultivation.

Recommended next stepHydroponics
Reservoir Volume Calculator

Calculate hydroponic reservoir volume from internal dimensions. Free online hydroponics calculator with instant, accurate results.

Hydroponics

Reference & details

How it works

Per-Plant Volume

Deep water culture needs large per-plant volume. NFT and drip systems recirculate from a shared reservoir sized for total system demand.

DWC: 2–5 gal/plant | NFT: 0.1–0.3 gal/plant (flow) | Drip: 0.5–1 gal/plant

Daily Consumption

Transpiration and evaporation deplete reservoirs daily. Size for 3–7 days between full changes or plan daily top-off volume.

Uptake ≈ 1–3% reservoir volume/day (mature plants)

Minimum Volume

Add 20% safety margin for root zone expansion and evaporation. Larger reservoirs buffer pH/EC fluctuations.

Min volume = Plants × Per-plant volume × Safety factor (1.2)

Updated: July 2026

Example Scenarios

4 large tomato plants at 5 gal each = 20 gal minimum. Use four 5-gallon buckets or single 25-gal tote with 20% margin.

200 lettuce heads on NFT channels with 50-gal reservoir — 0.25 gal/plant recirculated, changed weekly.

6 plants × 1 gal = 6 gal minimum reservoir. 10-gal tote provides buffer for 5-day change interval.

FAQ

Depends on system type. DWC: 2–5 gallons per plant. Recirculating NFT/drip: 0.5–2 gallons per plant minimum. Larger is more stable.

More volume buffers pH drift, EC changes, and temperature swings. Small reservoirs need daily monitoring; large systems tolerate minor imbalances.

Small systems: 1–2 weeks. Large commercial: 2–4 weeks. Change when EC drops significantly despite topping off, or pH becomes unstable.

Use food-grade plastic (HDPE, PP). Black or opaque blocks algae. Avoid metal containers — corrosion and ion leaching affect nutrients.

Commercial setups often maintain a separate top-off tank with pH-adjusted water auto-dosed to main reservoir. Size top-off for 1 week of evaporation/transpiration loss.

About Reservoir Size Calculator

Undersized reservoirs cause rapid pH and EC swings; oversized tanks waste space and nutrients. Enter number of plants, system type, and desired days between full changes to calculate minimum reservoir volume.