Hydroponics is a great way to extend the growing season for gardeners of all levels. And in many ways the ebb and flow hydroponic grow systems works a lot like your outdoor vegetable garden.
Ebb and flow hydroponic grow systems (also known as flood and drain) that you can build at home are suitable for the beginner to intermediate level gardener.
The photo in the header is the actual ebb and flow system built for this guide. Lettuce and rocket was planted from seedlings and I am starting to see true leaves.
In the article about DIY Deep Water Culture (DWC) systems you learnt that DWC is the best system to start with.
DWC is inexpensive and easy to get up and running with or without an air pump.
But where DWC is a net pot based system, the ebb and flow grow system gives you an indoor growing bed.
And you can basically grow anything in your ebb and flow growing bed – as long as the plant or herb is harvested above ground.
We recommend that you start with easy to grow vegetables and herbs such as lettuce, rocket and basil.
- Build an Ebb and flow grow system at home
- Guide to building a DIY Ebb and flow grow system
- Materials needed for an Ebb and flow grow system
- Advantages with an Ebb and flow grow system
- Disadvantages with Ebb and flow systems
- Is LECA (hydroton) the best growing medium for ebb and flow
- Intervals water pump with ebb and flow grow systems
- Water and nutrient level in grow tray when drained
- What can go wrong with an ebb and flow grow system
Build an Ebb and flow grow system at home
Before you start building I would like to point out a couple of things.
- For illustration purposes I am using clear containers for both the reservoir and grow tray . You should however use containers that block out sunlight to avoid problems with algae build-up.
- You need a grow light to be successful with ebb and flow hydroponic grow systems. I use a rather standard T5 LED armature that costs less than $30 (EUR 26) to purchase. You can however also use a LED bulb or any other strong light. This type of LED lighting works well for leafy greens and herbs.
- If you are planning to grow cherry tomatoes, Habanero peppers or even Padron peppers you will need even more efficient lighting. This type of high efficiency lighting is however also more costly, which is why I recommend you start with a more budget friendly T5 type LED solution and build from there.
- You want to place your light source close to your plants. But make sure your light source does not create too much heat for your plants. To keep it simple you are looking for regular room temperature.
- Start small. You will learn a lot by actually building your own ebb and flow grow system. And feel free to contact me if you have questions.
With those 5 caveats out of the way we are ready to start.
I will list all items needed for building ebb and flow hydroponic grow systems later on in the article.
Well, without context the list of items risk being more confusing than helpful. Feel free to skip forward but I do believe it will help if you first read along as we build the ebb and flow hydroponic grow system
Guide to building a DIY Ebb and flow grow system
The guide is divided into 18 steps to ensure that you can follow along regardless of level of knowledge and experience.
1. Clean the LECA (hydroton) pellets
LECA or hydroton pellets need to be thoroughly rinsed and cleansed before use. This process can be tedious and take some time. Be thorough, you do not want sand and grit from the medium to filter through to your reservoir.
2. Place the reservoir on an even surface
Make sure you place the reservoir on a stable and even surface.
3. Fill the reservoir container with water
Fill your reservoir container to approximately ⅔ of its full capacity.
4. Place water pump in reservoir
5. Drill holes in bottom of grow tray
Drill 2 holes in the bottom of the grow tray. Make sure to use the correct size drill bit for the tube connectors.
In our build we use a ½ inch/13 mm bit for the water pump hose and a ¾ inch/19mm bit for the drain tube.
When drilling in hard plastic you should always start with a small drill bit and work up to the size you need. Starting with a larger size drill bit (e.g. ½ inch/13 mm) will often lead to tearing the plastic material.
6. Attach tube connectors and secure to prevent leakage
The tape you see in the image is simply there to provide contrast in the image. You do not need to use tape. The tube connectors come with rubber gaskets that will seal tight to prevent leaks.
7. Attach tubes to tube connectors
8. Connect water pump to tube (½ inch / 13 mm)
9. Place grow tray on top of reservoir
I use the same size container for the reservoir and grow tray. This makes it easier to have a “safe” setup as the grow tray can be placed on top of the reservoir.
As you can see in photos below I simply use two pieces of wood and then place the grow tray on top of the reservoir.
But you can of course also place your grow tray on a table and place the reservoir underneath. And they can be of different sizes.
But do keep in mind that your pump needs to be stronger when you increase the distance the water needs to be pumped.
10. Start the water pump and run system for 15 minutes
Next we run the system and let the water circulate for 15 minutes. Check for leaks around tube connectors and make sure your system is not leaking.
Check carefully for slow drips around the tube connectors as this will be the natural weak point of the system.
11. Add LECA (Hydroton) pellets to grow tray (⅔ of capacity)
12. Add nutrition to reservoir container per instruction on packaging
13. Run system for 15 minutes
14. Check pH levels
Nutrient solutions usually come with a pH test kit.
Scope up some water nutrient solution in the test tube and add 3-4 drops of the test liquid.
Seal the test tube and shake it. Now compare the color of the liquid against the color chart. It should be indicated but you are looking for a slightly acidic environment with a pH between 5,0 to 6,5.
If you need to adjust the pH level by adding more nutrient solutions you need to run the system again before testing.
15. Plant your seedlings
This is the easy part. Make a whole and insert the seedling in the grow tray. There is nothing more to it.
16. Set timer to run water pump 15 minutes every 4 hours
17. Check LECA (Hydroton) between water pump intervals
When the system has run for a couple of hours you should check the LECA (hydroton) pellets in between the pump runs.
The grow tray is probably dry on top but that is fine. But you need to make sure that the LECA is retaining moisture ½ inch (1 cm) or so deep.
If not, you may need to increase the frequency and run the water pump more often.
Do not run the pump for longer periods, instead increase the frequency.
Materials needed for an Ebb and flow grow system
As you can see from the image you need a few items before you start building.
The main components of Ebb and flow hydroponic Grow Systems
- Reservoir container
I always use containers made from food safe materials. Containers are inexpensive and can be bought at most hardware stores.
- Grow tray container
I use the same type of container for the reservoir and grow tray. But if you do use different types or size the reservoir container needs to hold more volume in case of system breakdown or leakage.
- Submersible water pump
There are several submersible water pumps that are more than adequate for $10-20. For my latest build for this article I used a BOYU FP-350 Adjustable Water Pump with a 350 litre per hour capacity.
- Grow light
The level of natural light indoors will not be enough to successfully grow herbs and vegetables in an indoor ebb and flow system.
I use a T5 LED grow light with two 24W tubes. This setup gives me a total of 48 Watts, 3300 lumens and 6500 kelvin.
In an ideal setup you aim for 100 lumen per Watt. I fall below that with approximately 69 lumens per Watt but it still works well for me.
You also need the items below to build your grow system:
- Growing medium
I prefer using LECA (Hydroton) pellets but you can choose other growing mediums like rockwool or coco coir if you prefer.
- 3 feet (1 meter) plastic tube ½ inch (13mm)
The smaller dimension plastic tube is connected to the water pump to fill the grow tray.
- 3 feet (1 meter) plastic tube ¾ inch (19mm)
The larger dimension plastic tube is used as the drain tube. You can use the same size tubes for the water pump and drain. However, using a larger dimension for the drain adds protection in case of system breakdown.
- ½ inch (13mm) tube connector
Used to connect the water pump tube as it is pushed through the hole at the bottom of grow tray
- ¾ inch (19mm) tube connector
Used to connect the drain tube as it is pushed through the hole at the bottom of grow tray
- 2 Ebb and flow filter connectors
Attached to tube connectors to prevent medium (LECA / hydroton) in grow tray to block your tubes.
The filters are designed to let water pass while preventing the LECA from blocking your tubes.
The photo shows a filter connector attached to the water pump. But you should also attach a filter connector on your drain tube.
The filter connectors are mounted inside the grow tray.
- 2 Ebb and flow extension connectors
Used to elevate level of water inflow as well as water drain level.
The extensions are not necessary but help manage water level in the reservoir between water pump intervals.
- A timer
To allow water pump to run on 15 minute intervals
Advantages with an Ebb and flow grow system
The main advantages of an Ebb and flow system is that
- Inexpensive to set up
- You can grow plants with different grow cycles
- Energy efficient as pump runs on intervals
- Requires minimal supervision and maintenance
Disadvantages with Ebb and flow systems
There are not that many disadvantages with Ebb and flow hydroponic grow systems. Here are however some negative aspects that you should be aware of.
- Disease spreads more easily due to a shared growing bed
- The submersible water pump is a single point of failure
- Risk of water leaks if designed incorrectly
- Sensitive to power failures
Is LECA (hydroton) the best growing medium for ebb and flow
I always use LECA (hydroton) for ebb and flow grow trays. It is inexpensive, inert and can be reused.
There are, however, alternatives like rockwool and coco coir that are preferred by some growers.
One complaint about LECA is that it is fast draining. This would imply that the grow bed would dry out too quickly and leave the root systems in a dry growing environment.
I have never experienced this problem. I can however see several reasons why LECA – and any other medium for that matter – could dry out too fast.
- Your growing environment is too hot
- light source you use generates too much heat
- You run your water pump on too few intervals
And it could be that LECA is not the ideal choice if you are facing any of the above challenges.
Both rockwool and coco coir retain moisture longer than LECA which would make them better suited in a less favorable environment.
And ironically, I like LECA as it is fast draining and helps reduce the risk of root rot.
I do however sometimes use rock wool and coco coir in my grow beds. Especially when I develop seedlings where the seeds are small and difficult to handle.
Here I insert the whole rockwool or coco coir plug into the LECA filled grow tray.
Intervals water pump with ebb and flow grow systems
I often get the question regarding how often the water pump should run.
And there is no one right answer.
The general rule is that the water pump should fill your grow tray up to just below the level of your growing medium.
The drawing tube should drain all but a minimum amount of liquid from the grow tray when the pump stops.
The growing medium will retain the moisture while allowing air (oxygen) to reach the root system.
And then the cycle starts again.
My recommendation is to start running the pump for 15 minutes every 4 hours.
Check moisture levels just before the pump is about to start to make sure that there is still moisture in the grow tray.
It is fine that the medium dries up but it should not be completely dry.
If you find the growing medium to be too dry you need to run the pump more often. But not for longer than 15 minutes per interval.
Water and nutrient level in grow tray when drained
I always build my systems to completely drain the grow tray of liquid.
The growing medium retains enough moisture to keep the root systems healthy.
If you do not let your grow tray drain completely you increase the risk of root rot where the root systems sit in water with no access to air (oxygen).
What can go wrong with an ebb and flow grow system
There are several single points of failure with an ebb and flow system.
Still, they are rare and the system will usually bounce back when they are corrected.
Water pump breaks
If your water pump breaks your grow tray will dry out and the plants will die. This is of course a real risk but generally speaking water pumps last a long time and when they break we simply replace them.
Without electricity your light source and water pump will not work. But power outages do tend to be short-lived and while it is a risk it is usually easily managed.
Medium block drain or water pump
Tubes connected to the water pump and drain need to be shielded from medium like LECA, finding its way into the tubes and causing blockage.
Using filter connectors should be enough but I always take it one step further.
My recommendation is to use filter connectors and to cover these filters with a cheese type cloth to protect the tubes.
If a tube is blocked you could end up with a system that does not drain or fill up properly. And this can be difficult to spot if it is only a partial blockage.
Leakage of containers
Leaks will drain your system and cause problems for the water pump and your plants.
And it may also cause water damage to the floor or room where the ebb and flow grow system is placed.
This is always a bigger risk if the grow tray is larger in size than the reservoir container.
Pay attention to water levels to catch any leaks in time to minimize damage caused.
Water level too high in grow tray
If your grow tray doesn’t drain completely the root system of your plants will always sit in water.
This increases the risk of root rot that will risk spreading across your entire grow tray.
If you see that the water level is too high, reduce the strength of the pump.
You need to get the pH levels right for your plants to grow and thrive.
But you don’t need to worry about decimals. Keep the level in the recommended pH level range and you should be fine.
Measure pH levels each time you add any type of liquid to the system. This goes for both adding water or nutrition.
And always remember to let your water pump run one interval to mix your water nutrient solution before you measure.
Disease spread more easily
It is a lot of fun to have an indoor grow tray where you can plant and harvest continuously during the darker time of the year.
But a shared grow tray also means that diseases spread more easily between plants.
Our guide shows you how ebb and flow hydroponic grow systems that are relatively easy to build will allow you to grow kitchen greens and herbs all year round.
Ebb and flow is a little more work that a Deep Water Culture system (DWC) – but also much more versatile.
If you are completely new to hydroponics I recommend that you start with a DWC. There are fewer moving parts and it is quicker to get started.
But most people that start with a DWC are destined to have a go at ebb and flow hydroponics as well. That is at least my experience.