Size flood volumes for trays with realistic displacement. Add safety and reserve buffers for reliability. Produce printable results and shareable downloads for daily planning.
| Tray (L × W × D) | Units | Trays | Displacement | Safety | Reserve | Flood with safety (L) | Min reservoir (L) |
|---|---|---|---|---|---|---|---|
| 120 × 60 × 7 | cm | 1 | 35% | 10% | 20% | 36.04 | 43.25 |
| 48 × 24 × 3 | in | 2 | 30% | 15% | 25% | 84.85 | 106.06 |
| 100 × 50 × 6 | cm | 3 | 40% | 10% | 30% | 59.40 | 77.22 |
Ebb and flow systems depend on predictable flood depth across each tray. The calculator converts tray length, width, and flood depth into liters, then scales that volume by the number of trays. This gives the flood water needed for one cycle. Knowing the per-cycle volume helps prevent dry zones, reduces overflow risk, and supports consistent nutrient delivery during repeated floods.
Growing media occupies space that water cannot fill. The displacement percentage models this by reducing the nominal tray water space to an effective flood volume. Coarse clay pebbles often displace less than dense mixes, while packed coco or rockwool can displace more. Measuring a test tray, then adjusting the percentage, improves accuracy and keeps the reservoir sizing realistic.
Real systems lose volume in hoses, manifolds, and uneven leveling. A safety margin adds a buffer so the pump can complete the flood even when conditions vary. The reservoir reserve percentage then protects stability between cycles, leaving extra capacity for evaporation, plant uptake, and top-off mixing. Together, these factors define a minimum practical reservoir capacity rather than a theoretical number.
If you enter pump flow in liters per minute, the calculator estimates fill time for the safety-adjusted flood volume. This supports scheduling, because an overly long fill can warm solution and reduce dissolved oxygen. Compare the estimated time to your target flood duration and adjust pump size, plumbing restrictions, or tray grouping to keep cycles efficient and repeatable.
Use the results to standardize operations. Log effective per-tray volume, total flood, and reservoir minimum as baseline values. When you change media, add trays, or alter flood depth, recalculate and update your records. Consistent volumes simplify nutrient dosing, reduce operator guesswork, and make troubleshooting easier when plants show stress or growth slows. For audits, keep simple exports, and verify with a wet-run test after any plumbing change or leak repair.
Use the depth that fully wets the root zone without floating pots. Many trays run 2 to 8 cm, depending on container height and crop stage. Confirm by test-flooding and checking that all pots receive equal wetting.
Start with 30% for clay pebbles and 35–45% for denser media. For best accuracy, fill an empty tray to the target depth, then repeat with media installed and measure the actual refill volume difference.
Safety covers losses in plumbing, fittings, and uneven tray leveling during a flood. Reserve keeps extra solution available between cycles for evaporation, plant uptake, and stable mixing when you top off nutrients.
Flow ratings are usually measured at low head. If your pump lifts water or pushes through restrictive piping, actual flow can be lower. Measure real output into a bucket for one minute, then enter that value.
Yes, but calculate each tray group separately and add the safety-adjusted volumes. If floods run at different times, you can size for the largest single flood event, plus your chosen reserve buffer.
Differences come from tray ribs, plant pots, plumbing volume, and leaks. Adjust the displacement and safety values until the estimate matches a real wet run. Recheck after changing media, fittings, or tray counts.
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.