A Complete Guide to Your Hydroponic Ebb and Flow System: Hydroponics for Beginners

This post follows our research editorial guidelines.

Brock Ingham
Brock Ingham

Ticking timers, surging pumps and the swirl of draining water to the reservoir make the Ebb and Flow method of hydroponics a dynamic choice for the home grower. It’s a fantastic option if you’ve safely sailed across the choppy waves of hydroponic Deep Water Culture and are ready to learn something new. It pays to understand the mechanics behind the system before you get started, so let’s take a look at how you can try this exciting form of hydroponics.

Ebb and flow hydroponics 1

What Is Ebb And Flow Hydroponics?

Ebb and flow hydroponics is a system that alternately floods and drains the growing medium with a rich nutrient solution. This allows for roots to receive good nutrition while promoting healthy aeration. 

“The ebb-and-flow system is one of the simplest hydroponic systems to set up and use, but it still takes some experience and effort to master. The ebb-and-flow system costs are usually very low in comparison to many other substrate systems, because it doesn’t require any high tech, expensive components. “

Ted Goldammer, Greenhouse Management: A Guide to Operations and Technology

How Does An Ebb And Flow Hydroponic System Work?

All hydroponics relies on water to get the essential elements of growth into the roots. In an Ebb and Flow system, the plants are repeatedly flooded then drained out completely. It’s why these kinds of rigs are also called flood and drain systems.

In this technique, plants grow in a soilless medium contained in pots, buckets or baskets. These containers rest inside a broad pan called the ‘grow tray’. Water and nutrients are pumped into the tray until the water level is high enough to flood the plant roots.

It’s allowed to briefly absorb before the solution is allowed to drain back into the reservoir. A timer is used to repeat this cycle several times a day. Most will also have an air pump or other form of aerator in the reservoir tank to keep the solution well oxygenated. An overflow valve that prevents the rig overfilling is also common.

This technique is a popular choice for growing plants that are nutrient hungry but that also need a lot of air in their roots. The flood and drain cycles keep everything nourished and moist while providing ample airflow. Commercial growers value this system for how versatile it is across the growing season both for planting and harvest.

Hydroponic lettuce 1
Hydroponic lettuce

Choosing the Best Ebb And Flow System Bed Variations

How this fill and drain cycle is achieved can vary quite a lot, especially once you include growing beds built by hobbyists. I’ve found the average home hydro fan to be resourceful and creative, able to turn old bits and pieces into a diy ebb and flow rig that outperforms even the fanciest commercial ones.

All home gardener ingenuity aside, Ebb and Flow tends to follow a few basic variations.

Variation 1: Flood Table

In this variation pots straight up sit in a flat pan or tray with a system of tubes at one end and a pump at the other. The bulk of the growing area rests on some kind of table with the reservoir tank beneath. A submersible pump moves water from the reservoir into the grow tray. 

It rushes into the medium via holes in the bottom of the pots. With the tray on top it’s then just a matter of opening the drains and allowing that lovely rich nutrient solution to flow out and back to the reservoir.

These are super simple to set up and table kits are not hard to find at all. The system allows you get the the whole thing moving in no time at all. It’s basic components are easy to install – I challenge you to find an easier built than just slapping a tray of plants on a table!

It’s a versatile option too, and many leftover bits and pieces can be roped in to serve as containers. Really the only thing you need to spend big on is a pump, piping and a way to control the flow or flood.

On the down side this type of rig does need a whole table. You have to keep it flat so the more you want to grow the bigger the footprint. If you’re pushed for space in your grow room it might be hard to get enough space together.

Variation 2: Containers in Series

Ebb and flow hydroponic lettuce
Ebb and flow hydroponic lettuce

A more versatile type of ebb and flow system works by placing individual pots side by side in a channel formed from a gutter or custom cut length of pipe. Pots of medium are inserted into the channel. When the pump activates the channel floods from one end to the other.

It achieves much the same as a flood table and the system features many of the same elements. It uses strong submersible pumps, air stones and timers as well as overflow valves and the like.

This form of hydroponic growing is great for the technically minded hobbyist. Once you get the swing of it, this is a deeply versatile system. You can add extra lengths of channel or block off unused portions as plant growth demands. They’re also one of the best hydroponic systems for vertical gardening and food walls. 

Different Ways Ebb And Flow Systems Can Drain

Ebb and Flow Drain Kit

The easiest way to get started is to just up and get a kit. A standard basic ebb and flow drain kit should come with at least a single fill tube and a drain tube to match. These are pretty straightforward and are just an inflow and outflow.

Good quality kits will often include an overflow valve too. For bucket systems with a recycled tray you’ll have to drill your own holes, but if you’re not up for that consider using a prefab one instead. They generally have placements for holes pre-cut and are easy to set up.

Bell Siphon Kit 

A bell siphon is almost a kind of magic. It’s a clever way to remove the solution without any electricity or timers. They work by leveraging how air pressure influences the flow of water. At its simplest a bell siphon is a tall outflow pipe capped by a long cover. The lower edge of the cover sits close to the bottom of the tray or channel, with a gap at the top near the entry to the outflow itself.

As the water rises, the level inside the cover rises too. By the time the water level reaches the top of the outflow a vacuum forms inside the siphon. Air pressure then forces all the water in the tray or channel to empty. This means you can skip the timers and just let the water pump run continuously. The siphon will do the hard work for you.

While you can build your own, the process is pretty fiddly. It’s easier just to buy a kit at the same time you grab all the other bibs and bobs your system requires.

Choosing the right growing medium for Ebb and Flow

Choosing the best medium for your type of system comes down to what the plant’s roots need to thrive. Thirsty plants that need constant nutrition do better with organic materials that hold solution for longer. Others will thrive with roots that are dry for short periods and require a chunkier organic medium.

The medium will also impact how often the tray is pumped full. Material with a low water holding capacity needs to be flooded frequently to maintain good hydration. Typically this is inorganic material like clay pebbles, perlite or sand. Other substrates hang onto the nutrient solution well and doesn’t need quite as high a flow rate. Coco peat and Rockwool are good examples.

What grows well in an ebb and flow system

Outdoor hydroponic lettuce
Outdoor hydroponic lettuce

Any plant that will fit in your rig is going to thrive with the right tinkering. Trailing plants like oregano or strawberries look great in vertical gardens and any with compact roots like lettuce do well in table setups. Popular ebb and flow crops include:

  • Seedlings
  • Leafy greens like lettuce
  • Strawberries
  • Cherry tomatoes
  • Cucumbers
  • Peppers

What does not grow well in an ebb and flow system

There are some limitations to what you can grow in ebb and flow. While these systems are great for compact plants and those you harvest as you grow, deep rooted plants and those with long lifespans tend to run out of room. Channels only have so much space, and you really don’t want massive buckets of medium with huge deep trays to flood. Examples of crops that don’t work well in ebb and flow include:

If you want to try growing plants like these you might want to look into a more effective hydroponic technique. Drip irrigation works well for large shrubs and root veggies and is just as flexible for indoor growing as ebb and flow. 

FAQ

Ebb and Flow Vs Deep Water Culture: Which is the best hydroponic system?

The best system for you is always the one that takes into account how much space, money and time you have to spend. Knowing what crops you like to grow helps too.

I prefer passive Deep Water rigs for leafy greens. They basically grow themselves! I can seal them away and be assured that they have everything they need to keep them going until harvest. This system is also very cost effective to set up and run, allowing me to pepper my growing space with tiny rigs here and there as space allows.

But for fruiting crops Ebb and Flow has some distinct advantages. An Ebb and Flow system allows me to change the solution as the plants mature and change. I can promote foliage when they are becoming established and switch to a nutrient profile more suited to fruit later in the season. Using a vertical growing wall also allows me to enjoy the plants for their beauty and make good use of what would otherwise be dead space.

If all you want to grow are greens, Deep Water is going to give you more bang for your buck. But if you want to grow fussier fruit and veg, consider an Ebb and Flow.

How Often Should you Flood and Drain an Ebb and Flow Grow System?

Your choice of plants and the water holding capacity of your substrate are the determining factors for how often you should flood and drain your rig. For an absorbent growing medium with low needs plants three to five cycles a day will likely do the job.

Thirstier ones or those in inorganic material may need up to eight cycles a day. The temperature inside your grow room also plays a part. Warm weather makes for thirstier plants and will also dry your medium out more quickly.

Keep an eye on your plants and they’ll let you know if you need to up the frequency. Watch for classic signs of dehydration like limp leaves or drooping stalks.

What are the disadvantages of DIY Ebb and Flow?

Like all home grown hydroponics system the biggest disadvantages come down to cost – both in terms of purchasing and running the system.

Because this system involves near constant pumping of water it uses more electricity than Deep Water Culture passive setups like wicking beds. Using a passive wick for the nutrient solution uses no power at all and is cheaper to run. Pumps, timers and valves also cost money. You can’t cheap out – badly made parts kill plants.

You also have to watch out for high humidity. The flow of water can result in growing areas that are very humid, especially beneath the leaves. After all the flood tray keeps all that moisture quite low.

It’s a substantial disease risk for most crops. Lettuce for example is prone to leaf disease and basil is vulnerable to downy mildew. Keep in mind the growing needs of your crop and provide extra ventilation if required.

Final Thoughts

 The selection of ebb and flow grow systems can seem tricky. Using the system can seem fiddly too. But the system holds some real advantages for the indoor gardener. It can be as beautiful as functional, and I know I love watching my trailing wall of strawberry vines pop into bloom and then swell with bright ruby like fruit. It’s one of the best grow choices for the intermediate hobbyist who’s ready to branch out and grow themselves!

Email icon
Don’t Leaf Me Hanging! 🍃 Join the Club!