More people than ever are getting into home growing vegetables and other plants. The most popular type of hydroponic system, called Ebb & Flow or Flood & Drain (let’s call it EF/FD for simplicity’s sake), is also our recommendation — it is simple to use, easy to understand, and does an excellent job of delivering both nutrient solution and oxygen to the roots.
There are also a wide variety of EF/FD systems to choose from, from pre-fabricated, professional-level systems, to simple, homemade setups that are much more inexpensive and frankly, a better option for brand new growers who are growing just for personal enjoyment.
For readers who want to get started quickly, we have put together a very clear, step-by-step guide to making a super-simple, yet effective and sturdy EF/FD using household storage containers and a few things that you can pick up at your local big box or home improvement store, aquarium shop, and hydroponic outlet. Or you can pick everything up on the internet, if you’d rather not venture into the great outdoors.
Step One: Collect Your Materials
For the reservoir and table combo, you will need to purchase two plastic storage containers, preferably opaque because you want to limit the amount of light that penetrates your nutrient solution. Light feeds algae, which you do not want growing in your reservoir.
Most manufacturers mold and sell containers in multiple depths but the same width and length, for stacking purposes. Buy the thickest, toughest-looking ones you can find in the size you need, and make sure that you remember to leave room to move around in your grow room.
You will also need to purchase a small water pump, like the kind that would be used in a decorative fountain. You don’t need a huge pump, just enough to move the water from your reservoir [the bottom of your large storage bin (A)] to your flood tray (B).
You will also need a piece of plastic tubing to connect to the output from the water pump to the upper section, “flooding” the flood table. The water pump will be plugged into a wall outlet via a timer, which will turn the pump on at set intervals, watering your plants, then draining back into the nutrient reservoir. The draining of the nutrient solution will be explained more thoroughly in the next section.
In addition to the water pump, you will also need at least one aerator, like the ones typically used in aquariums, which will not only oxygenate your nutrient solution, which is good for your roots, but will circulate the solution as well.
Other items you need:
• Electric drill, with assorted bits. This should be the only tool you need.
• Electric timer to control your water pump.
• Screening to cover the top of the overflow pipe to keep extra particulates, like your growing medium, out of your reservoir. Can be held on using a rubber band.
• Growing Medium. I recommend using rockwool cubes to hold your plants, and then Leca (terra cotta pebbles which are a staple in hydroponics) to line the bottom of your flood table and fill in the area around the rockwool cubes. Your roots will grow into this area, so make it nice!
Step Two: Drill, Baby, Drill
You now have two plastic bins, that fit together perfectly. What you need now are ways to move water from the reservoir into the flood table and back to the reservoir again. That is where we bring in your water pump and handy dandy drill.
Before you do ANY work, do a stress test on your bins to make sure that they can handle the weight of the nutrient solution and plants that they will need to hold.
Your Upper Bin (Flood Table)
Start by drilling the necessary holes into your upper bin, the one which will become your flood table.
In the upper storage container, your flood table, you will drill two holes on opposite ends of the table from one another, but still centrally-located.
The first, (A) will be the exact size of the tube that comes from your water pump into the flood table, where it will fill the table with nutrient solution from the reservoir.
The second, (B) will be the exact size of your overflow pipe, which will be much wider than your first hole. The width of this pipe is totally up to you, but keep in mind that this pipe is also where you will top off your nutrient solution once you have started your grow.
How high you allow the overflow pipe to stick up from the bottom of the flood table will determine how deeply your nutrient solution will fill your flood table. Most growers have set their overflow pipes to the same height as or just below their rockwool cubes (or whatever they are using to immediately hold their clones at planting).
A third set of small holes © should be drilled into the lowest point of the flood table, which will most likely be dead center. These will look and act somewhat like the drain in your shower, though the holes should be much smaller; I’d recommend no larger than 1/3 to 1/2mm.
During the watering cycle, nutrient solution will drip through these holes back into the reservoir, and then recycle back into the flood table via the pump. Once the timer triggers the pump to turn off, the nutrient solution in the flood table will slowly drain back into the reservoir for use in the next cycle.
Your Bottom Bin (Reservoir)
Next, drill the one hole that you need for your deep, lower bin, which will be your reservoir. This hole needs to be large enough to fit:
• The power cord for your water pump, the tube(s) for your aerator(s).
• Do not make the hole any larger than you need, so as to lower the risk of insects, mildews, etc., getting into your reservoir.
Step Three: Put It Together
Once you have all your holes drilled, it’s time to put the whole thing together, which is a pretty quick process.
• You have made a hole the size of this pipe, so just slip it into its spot, keeping in mind the height info that we have been giving you.
• You will use this pipe not only as the way to keep your water level regulated and to keep your table from flooding, it will also be easiest way to get water and nutrients into your reservoir. To keep particulates (like bugs, dust, hair, and pieces of growing medium) out of your pipe, simply cover it with a piece of screen (from a hardware store) held over and onto the pipe by a rubber band. When you need to add water and/or nutrients, just take off the screen.
• Set up your water pump in the reservoir, however its manufacturer wants it set-up. Some pumps have suction cups to keep themselves in place — use them if you have them.
• Attach tube from pump through the hole you drilled and into the flood table. (If you have trouble with either this tube or the overflow pipe staying in place, buy a non-toxic epoxy glue).
• Run the power cord through the hole that you drilled through the side of the reservoir, then plug it into your timer, which is plugged into your wall. You use the timer to set up when your plants will water, and for how long.
• The frequency and length of time that you water your plants is a debated topic among growers, and it also varies based on how close your plants are to their light source, how humid or dry your environment is, where you are in your grow cycle (flowering drink way more water than it does while vegetating), among a variety of other factors.
• Choose long, thin aerators for a couple of reasons: firstly, they spread the bubbles out well, adding to a proper mix; secondly, you will need to fit them through that hole that you drilled in the side of your reservoir into the inside. The plug and motor will be outside the bin, so you just need to send the hose and aerator itself through that hole.
Get It Together:
• Now it’s time to put the top section on, nesting the flood table inside of the deep bottom reservoir.
• Fill up your reservoir with your nutrient solution, following the instructions on your nutrients for however many liters of liquid your reservoir holds. Most nutrient companies measure using the metric system, so if you pour your water (reverse osmosis, please) into the reservoir in gallons you will need to do a little math to know how much nutrient to add in milliliters. (Good news: there are a ton of free conversion apps for iOS, Android, etc.)
• Once you have it all settled, you can start filling your flood table with your growing medium of choice. Like I said, my personal preference for this type of system is rockwool cubes surrounded by LECA pebbles, but one of the great things about hydroponics is our ability to customize — your plants will grow in a variety of mediums. Just never hesitate to ask questions and seek information wherever you may find it.