Hydroponic Flood & Drain

what is a hydroponic flood and drain system?

The flood and drain system, also known as ‘ebb and flow’, is a simple and efficient hydroponic method of growing. It uses a water pump to flood the roots of the plant, and then allowing the water to run back down into the water reservoir below. This method is a great choice for both beginner and advanced growers and can be easily set up at home using DIY materials. It can also fit into a relatively small space and can be used for both indoor and outdoor growing. 

how does the flood and drain system work?

The basic parts of the flood and drain (or ebb and flow) system are a main reservoir or water tank. This will hold water and nutrients. A grow table will sit on top of the reservoir. This is what holds your plants. The system can work with just one plant or several plants in one tray.

A water pump is placed into the reservoir, where water is pumped up into the grow table. The water will soak all the roots of the plant and then gravity will allow the water to flow back down into the reservoir.

By soaking the roots in water, the plant will be deprived of oxygen, and so when the water has run back out, the plant will make up for it’s lack of oxygen by taking in as much as it can, when the roots are dry. Likewise, when the roots are drying out, they will become thirsty for water, so when the water is pumped back up, the plant will take in as much as it can. This has proven to be an effective way of growing.

The system is linked up to a timer, which will flood the plants at varying intervals in the day (this can be once per day or several times a day). 

Flood and drain diagram

how often should you flood your plants?

The amount of flood and drain cycles each day will vary depending on the set up of your system and the climate you live in. In hot and dry climates, or if growing outdoors, try to flood the plants around 4 times each day. In warm climates, or if your growing medium is fast draining, then try flooding your plants 3 times a day. For slower draining growing mediums, or cooler and humid climates, twice a day should be fine.

The plants should be flooded for around 15 minutes and take the same amount of time to drain back out. Just make sure the roots do not dry out too much.

During the vegetative period, you should be increasing your lighting (around 6 extra hours a day). Because of this, you should put through one more plant flooding cycle each day, during the vegetative stage. 

advantages of the flood and drain system

  • It’s very cheap to set up and can be easily created with basic household/ gardening equipment
  • Once set up, it’s easy to maintain
  • Building your own system is not too complicated as with other hydroponic systems
  • It produces quality plants 

disadvantages of the flood and drain system

If your pump or drainage system is broken, this can easily ruin all of your crop, so it’s vital that you do keep checking regularly that the system is in working order. The water flowing back into the reservoir can change the pH levels of the nutrient solution. Again, you will need to check the pH levels and replace the water each week. 

baby growing plant

what you will need for a flood and drain system

  • Reservoir or water tank- this can be as simple as a plastic storage box
  • Grow table- for your plants to sit on
  • Submersible water pump (a simple garden pond one will do)
  • Air stone- to produce more oxygen in the water
  • Air pump- to push the oxygen around the water
  • Timer- to control the flooding intervals
  • Black Tubing- for the drainage tube and water pump. The drainage tubing should be a little bigger than the tube pumping the water up to the plants
  • Growing medium- for your plants to sit in 

how to set up your flood and drain system

  • Drill 2 holes in the bottom of your grow tray/ flood tray.
  • Drill another 2 holes in the lid of your reservoir. These should match up to the holes in the grow tray.
  • Put your water pump and air stone into the reservoir.
  • Sit the grow tray on top of the reservoir lid and attach the two together.
  • Fit some black tubing to your water pump and push it up through one of the holes at the top of the reservoir.
  • Fit some black tubing through the other hole, so the flood water can drain back into the reservoir. Make sure to put a filter on this, to stop any of the growing medium from falling into the reservoir.
  • Fill up the reservoir with water and nutrient solution
  • Put your plant pots in the flood tray
  • Attach a timer to your water pump and set it to the required intervals
  • Turn on the pump and watch your system do its thing.