Related guides: setup checklist · NFT hydroponics guide
Ebb-and-flow systems periodically flood a growing tray with nutrient solution and then drain it back to a reservoir. The cycle wets the media, delivers nutrients, and replaces air around the roots as the tray drains.
The basic cycle
A pump moves solution into the tray for a set period. A standpipe or drain sets the flood height, and the solution returns to the reservoir after the pump stops. The cycle length depends on the media, tray depth, crop, temperature, and how quickly the root zone dries.
Why media and drainage matter
Perlite, clay pebbles, coco-based media, and other materials hold different amounts of water and air. The tray must drain reliably without leaving a stagnant low spot. Test the system with plain water, mark the working level, and check every fitting before planting.
Keep the failure mode visible
A stuck pump can overfill a tray; a blocked drain can leave roots saturated; a dry reservoir can stop the next cycle. Use a stable reservoir, protect the pump intake, leave access for cleaning, and never hide the system behind furniture.
- Run several empty cycles before adding nutrients.
- Confirm the tray drains completely enough for the chosen media.
- Use a timer you can inspect and replace.
For the next step, see the DWC setup guide.
Set the flood around the medium
The pump should wet the growing medium thoroughly and then allow the tray to drain far enough for air to return. Timing depends on the medium, tray depth, crop, temperature, and pump rate. Watch what the plants and media do instead of copying a timer setting from an unrelated system.
Before planting, run plain water through several complete cycles. Confirm that the high points wet, the low points drain, the return line cannot back up, and the pump does not uncover itself. A level tray, open drain, and easy access matter as much as the timer.
Media and failure checks
Choose media that supports the crop while draining predictably. Fine particles can collect in the pump or drain, while a very fast-draining mix may not stay evenly moist between cycles. If one corner dries, check the tray level and flow path before increasing fertilizer.
- Inspect the pump intake and drain after moving the system.
- Keep light out of the reservoir and unused media gaps.
- Leave space to remove a tray without spilling solution.
- Test the system again after roots and plant weight change the flow.
Flood-and-drain is a flexible recirculating system, but it rewards observation. Pair this guide with the setup checklist and compare it with other system choices before buying parts.
