Master hydroponicist and chilli fanatic, Jukka Kilpinen, shows us just how easy it is to custom build your own flood & drain (ebb & flood) hydroponics system!
After growing chilli plants with different hydroponic systems
for nearly ten years, one hydroponic system still stands clearly
ahead of them all: Flood & Drain aka Ebb and Flow.
Before using it or seeing in action, it may seem a little
complicated but after you get it, I believe that it's probably the
most simple system there is!
Flood & drain offers many advantages:
- efficient yet still very simple! Gives unbelievable crops with
decent nutrients and in a location with plenty light.
- possible to use any growing tray sizes you want with the same
principle from trays for tiny seedlings through to systems several
meters long! You don't need super powerful pumps for flood &
drain either, any low-power aquarium pump will do, as the objective
is simply to have the growing container flooded with nutrient
solution for a few minutes or even seconds.
- Plants can be transferred directly to flood & drain systems
- Flood & drain develops very strong decent roots with chilli
peppers that make it perfect for transferring the plants when
needed. I believe that flood & drain achieves this much better
than any other hydroponic systems.
- You can grow all of your plants in one system and easily
re-arrange or transfer them to other hydroponic systems or even
soil.Nno hydroponic pots of any kind are needed.
- Flood & drain's simplicity makes it very reliable so plants
can be left alone for even weeks. (If the nutrient reservoir is big
- Easy to integrate into balcony, a table or growing corner. It's
an incredibly versatile system that can be built as you like to use
it and as you want it to look.
- Very easy to maintain, if you build your ebb properly, changing
nutrient solution after each two weeks or so will be very easy and
- Very safe which makes it ideal for indoor growing. Properly
planned flood & drain won't leak the nutrients to the floor of
your apartment as the growing container rests directly on top of
the nutrient container. All inlets and holes are in a place where
dripping doesn't matter.
- Flood & drain is also ideal for indoor growing as it's very
silent even when the pump runs.
Okay, let's get started with some planning:
First you need to work out what kind of space you will have
available for you plants so you can scale your system
It's also important to remember that your plants can grow HUGE
meaning high water and nutrient requirements! A smaller reservoir
will mean that you need to add water more often.
No matter how small or big a system you build, the principle is
exactly the same as shown on this building example.
The growing container (the upper part) can be any shape you
wish. For practical reasons, sizes like 60 x 60cm or 80x80cm and
bigger are a good plan. If in doubt go for squares or near square
rectangles. Be sure to leave adequate space around the system. Your
chilli plants will thank you for it.
For bigger systems I would recommend a long (but not too wide)
system. My "monster" 30 cm x 5 meter flood & drain system has
been ideal for efficient and easy growing.
Back to the basic principle: the plant container (upper part)
will be filled with expanded clay pebbles. Some growers mix in 50 /
50 diatomite too for added plant-available silica. (If you go this
route, be sure to reduce the frequency of your irrigation as
diatomite is more absorbent than clay pebbles.)
I usually start my seedlings off by germinating them in rockwool
cubes and then transferring into rockwool blocks. Sometimes I plant
aeroponic cuttings (without rockwool or any other propagation
media) and that works also well. Just be extra careful with those
roots when transplanting.
How the System Works
The timer is first set to pump nutrient solution to the upper
tray twice a day.
It floods the upper tray and waters the roots and expanded clay
balls with nutrient solution. After a minute (or any time suitable
for your ebb) the timer will turn off the pump and the nutrient
solution drains back to nutrient container back through the pump.
(Make sure your pump allows water to drain back through it. Don't
worry - those beautiful people at your local grow shop will sort
you out.) An overflow drain ensures that any excess water drains
back to reservoir before the expanded clay starts to flow. Best
practice is to set the timer to stop the pump when the water
reaches overflow tube. A digital (rather than segmental) timer
affords the grower more accuracy in setting irrigation times. The
overflow should be adjustable so as to make the incoming nutrient
solution deep enough to reach the roots of the plants.
Errrr … that's it!
So why it is so efficient then?
First of all, with a digital timer, the watering can be adjusted
for different chillies as some like it more wet and some like more
dry conditions. And of course its good to water more during the
summer when it's hot and less during the winter.
Flood & drain seems to be especially ideal for growing
chilli peppers, tomatoes, peas, melons etc. Allowing the growing
media to dry out more between irrigation cycles encourages your
plants to flower. Keeping the media wetter will generally produce a
more vegetative effect.
Second: Whilst some growers are building very complicated
aeroponics systems at home, I'm not so keen as you need expensive
pumps that consume more electricity and tend to also make quite a
When your root zone is flooded in a flood & drain system,
any stale air is forced out. When the system drains, fresh air in
pulled back in. Happy, happy roots! Another reason why it's so
important to have a well-ventilated growing environment.
Anyway, back to the build. You need to find an appropriate
container to house your plants in. The one chosen here works very
nicely as an example. Transparent containers (for either the upper
or lower tray) may look quite funky but they are far from ideal
because roots and your nutrient solution don't like light at all.
This can be prevented by covering the container with plastic but
why not just go for an opaque container in the first place? :-)
Here's the two-part box chosen for this example. See how the top
box sits nicely on top of the bottom box. You can use two
completely different boxes and just place the growing container on
top of the reservoir or even use table in between.
Here are other parts used in this project:
Any place where water flows will need to be filtered using a
suitable material like plastic mosquito netting.
Here's the submersible pump used with this Flood &
This same pump works just as well with a much, much bigger Flood
& Drain system.
Okay - so you have your stuff in place. Now it's time to
build the system!
FIRST - you need to drill TWO holes through the bottom of
the container. One for the inlet (water in) and a slightly larger
one for the overflow (water out.)
For the inlet part the hole doesn't have to be exact, just drill
with this piece and try to fit the inlet when the hole looks close
enough. If it doesn't quite fit, make the hole a tiny bit bigger
and try again until it slots in nicely.
Drill the hole for the overflow. In this case, this one has to be
more exact. In other words, it has to be just smaller than the
If you accidentally make the hole too big, don't worry, just
replace the overflow tube with bigger one. Actually, the bigger the
overflow tube is, the better it will work!
Ok, so at this point, the system is almost done!
Now cut a piece of the hose for the pump and inlet.
You need to estimate the length of the hose needed in between
the pump and the outlet and attach it to the inlet.
At this point you can attempt to place the growing container on
the nutrient reservoir to see if it fits. If the hose is too long,
just cut piece by piece off it until it fits perfectly.
Okay, the actual work has been done now. Lets look at
the system now:
Now it's time to test-drive the system. Her "maiden flood," if
Pour in your washed, expanded clay balls or a similar
(preferably non-restrictive) growing media.
Make sure your clay balls are washed before you put them into
the growing tray. I find it's easiest to wash them in the bag they
come in, just poke some holes at the bottom of the bag and run
water through until the water coming out is quite clear (rather
than brown and dusty.)
Fill the reservoir with plain water, halfway or so, it doesn't
matter at this stage.
Now you need to time how long it takes to flood the upper tray.
Prepare to start a stopwatch (most mobile phones have them these
days.) Turn the pump on! Start the stop watch.
Keep an eye on the water level then turn off the stopwatch when
the water starts pouring from the overflow. Take a look at your
stopwatch. This is the approximate ideal time needed to flood the
Adjust the pump run times according to available light. If the
light hits the plants at 8:00am, you can flood the growing
container around then or maybe 30-60 minutes after. Then, for
example, you can schedule additional floods at 12:00pm and at
4:00pm or 6:00pm or whenever the sun / artificial light fades out /
turns off. There's no need to run the pump during the darker
At this point, your system is ready for the
You can move germinated plants or bigger seedlings into the
You can also use your flood & drain unit as seedling growing
system if you wish.
I start ALL of my plants hydroponically which makes growing much
easier and more fun.
The actual planting is very easy. Just dig out some
expanded clay and place the rockwool cube in place and cover it
with expanded clay. This process only takes a couple of
As I mentioned earlier, an ideal amount of plants to grow in
this system is 2-4. Just let the plants grow towards separate
directions and support them if needed.
Most people who have tried this flood & drain system swear
it's the best hydroponic system they've ever used! And who am I to
disagree? There are so many positive aspects when it comes to
growing your favourite plants in flood & drain and the yields
Oh and one final word, if you can't be bothered to build your
own system, there are loads of fantastic ready-to-use flood and
drain systems available at your local grow store!
Happy hydroponic gardening!
For more info check out Jukka's website at: www.fatalii.net/growing/
Words: Jukka Kilpinen