Plan safer solution capacity for every DWC grow. Avoid swings with buffer and refill timing. Download results as CSV or PDF for records easy.
| Scenario | Plants | Uptake (L/plant/day) | Evap (L/day) | Refill days | Safety % | Working fill % | Recommended capacity (L) |
|---|---|---|---|---|---|---|---|
| Leafy greens, weekly top-up | 8 | 0.35 | 0.50 | 7 | 15 | 80 | ~35.3 |
| Warm room, higher evaporation | 12 | 0.45 | 1.20 | 6 | 20 | 75 | ~62.2 |
| Small herb setup, frequent refills | 4 | 0.20 | 0.20 | 3 | 10 | 85 | ~4.7 |
In deep water culture, solution volume acts like a thermal and nutrient buffer. When plants transpire aggressively, the level drops faster than expected. Sizing from measured daily uptake helps prevent exposed roots, pump cavitation, and sudden EC spikes between refills. Track drawdown for three typical days, then average to reduce noise from weather and stage changes.
Leaving headroom above the working fill reduces spill risk and improves gas exchange. Air stones create turbulence that drives oxygen transfer, but the system still benefits from stable levels. A larger reservoir slows concentration changes, supporting steadier dissolved oxygen availability at the roots. Keep tubing clean and verify airflow so your oxygen input matches the reservoir size.
Water temperature changes more slowly in higher volumes, especially when the tank is insulated or shaded. Warm solution holds less oxygen and can accelerate biofilm growth. Extra capacity reduces the rate of temperature drift during lights-on periods and supports safer operating ranges. If the room runs hot, consider reflective wraps, chillers, or moving the reservoir outside the canopy footprint.
Concentrate dosing is most reliable when calculated from the working volume, not the container’s brimful capacity. Mix thoroughly, then recheck EC and pH after circulation. Exporting results supports consistent recipes, repeatability across grow cycles, and clear documentation for troubleshooting. Log top-offs separately from full changes, because dilution shifts ratios even when EC looks steady.
A quick dimension check confirms whether your reservoir matches the recommended capacity. For rectangular tanks, usable fill height depends on lid clearance and bulkhead placement. For cylindrical buckets, diameter controls area strongly. If capacity is short, lower refill days or add a control reservoir. When upsizing, also confirm pump return rates and drain-down volume, so the system stays stable during power loss. This keeps roots submerged and avoids overflow.
Most growers use 70–85% to keep safe headroom. Higher fills reduce required capacity but increase splash risk. If you use aggressive aeration or recirculation, keep more headroom to prevent spills.
Mark a starting level, run the system normally, and measure the level drop after 24 hours. Repeat for three days at similar temperature and growth stage. Use the average for more reliable sizing.
Yes. Air movement, warm lights, and open lids can evaporate meaningful volume. Include a system-wide daily evaporation estimate so your refill interval stays realistic, especially in dry rooms or near fans.
Bigger volumes generally stabilize EC, pH, and temperature. However, they also take longer to adjust when corrections are needed. Choose a size that balances stability with practicality for changes, cleaning, and nutrient mixing.
Many setups change every 7–14 days, depending on crop, temperature, and cleanliness. If pH drifts rapidly, roots smell off, or you see slime, change sooner and sanitize equipment to reset conditions.
Container labels can be misleading, and usable volume is reduced by lids, net pots, fittings, and minimum water lines. Dimension-based capacity confirms the real fillable space and prevents undersizing that exposes roots.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.