A simple to build ebb and flow hydroponic system made (mostly) from IKEA containers.

Ebb and flow hydroponic systems are a great way to get started in hydroponics and make a wonderful educational project for children. Not to mention you can grow yummy food easily and inexpensively in your own home year round! A system like the one shown here is the perfect size for a kitchen herb garden.

A basic ebb and flow hydroponic system consists of a growing bed, porous growth media, a nutrient reservoir, pump and a timer. The system works by periodically flooding the growing bed with a nutrient solution and then allowing the nutrient solution to drain from the bottom of the growing bed. As the nutrient solution drains, oxygen is drawn into the growth media from the top. Because the growth media is porous, it retains moisture and nutrients, and allows oxygen to get to the roots of the plants.

Supplemental lighting is necessary if you will be growing plants indoors. Specialty grow lights are available but you can achieve good results using common light fixtures and 100 watt equivalent "daylight" compact fluorescent bulbs available at most home stores. Generally, I like to locate my hydroponic system near a window to take advantage of natural light and add one or two supplemental light sources as needed. Just make sure that you can adjust the height of the light fixture so that it can be easily re-positioned as the plants grow.

Step 1: Materials and Tools Needed

Materials:
1. IKEA SAMLA container with the tote insert. (Any nesting plastic containers will work as long as the outer container is approximately twice the volume of the inner container or larger.)
2. An adjustable desk lamp. You may use more than one if you need more light. (The IKEA TERTIAL lamp works well.)
3. A small submersible fountain pump. (Available inexpensively at Harbor Freight tools)
4. Two plugin timers, one for the pump and one for the lamp.
5. 24" clear vinyl tubing sized to fit the outlet of your pump. This will generally range from 1/4" to 1/ 2" for fountain pumps.
6. One nylon hose barb to MIP adapter. (One side has a barb that you can press the vinyl tubing over, the other side has threads. I got mine at Lowes.) You can use either a straight or right angle fitting.

Tools:
A hand drill
3/4" or larger step drill bit
tin snips or heavy scissors to cut the tubing

Step 2: Preparing the Growing Bed

The inner nesting container will hold the growing media and serve as the growing bed. A hole must be made in the bottom of the container which the nylon adapter will thread into. The hole should be approximately in the middle of the container to one side of the center ridge.

The adapter that I used required a 1/2" hole. Yours may be different so be sure to check the size. It is important when making the hole not to make it too big. I recommend using a step drill bit which allows you to gradually increase the size of the hole. You can always make the hole bigger but is really hard to make it smaller!

Thread the nylon adapter into the hole. It should be a rather snug fit. You only need to catch a few threads for a secure fit. The top of the adapter should only protrude about 1/16" into the growing bed.

Step 3: Prepare the Pump

Attach the 24" piece of vinyl tubing to the pump. The pump I used has a a 5/16" outlet port which makes for a snug fit with 1/4" tubing. It is helpful to carefully warm up the end of the vinyl tubing (a hair dryer or heat gun works well) to make it a bit more pliable and easier to slip over the outlet port. You should not need a hose clamp. However, if the tubing is slipping off after you press it over the pump outlet, a hose clamp or a dab of crazy glue will fix the problem.

Step 4: Attach the Pump to the Growing Bed

Next push the free end of the hose over the nylon barb fitting on the growing bed. You will need to push fairly hard. Be careful not to pull the fitting out of the hole.

Note: If you slip and pull the fitting out and it will not thread back in snugly, hot glue is your best option.

Optional: If you have a bit of plastic screen, tape it over hole in the nylon adapter. Depending on the growing media that you select, the screen will help prevent clogs. (More on this later)

Step 5: Position the Pump

Place the pump in one corner of the outer box. Most pumps come with little suction cups attached to the bottom to hold the pump in place. You should have enough slack in the tubing to lift out the growing bed and place it across the top of the outer container. This will make filling and cleaning the reservoir easier.

Once you have your pump positioned, make a hole in the outer container for the plug. The pump that I used had a plug that was slightly over 3/4", just bigger than the stepper bit that I was using. I enlarged the hole by holding the drill at an angle and reaming the hole a bit larger with the bit.

Make sure that the hole for the pump cord is slightly above the bottom of the growing bed. You will be filling the reservoir with growing solution just shy of the bottom of the growing bed.

Step 6: You're Almost Done!

You need to add gowning media to the bed. I like to use a combination of rock wool cubes and expanded clay pellets as growing media but many alternatives exist. There is plenty of good information available online. Just search for "hydroponic growing media" and you will be presented with a plethora of options. In order to prevent clogs and and keep the growing media from falling into the nutrient reservoir, I like to tape some plastic mesh over the drain holes (see the photo). The plastic mesh from fruit bags that you get at the grocery store works very well.

You should fill the bed with growing media to a depth just below the overflow drain. The overflow drain allows the nutrient solution to drain back into the reservoir while the pump is running. The IKEA container has a built in handle that makes an excellent overflow drain. If your container of choice does not, simply make a hole in the side of the growing bed container with the stepper bit.

Your plants will need abundant light. Expensive grow lights are available but I have achieved good results using 100 watt equivalent "daylight" compact fluorescent bulbs which are available inexpensively from home stores.

One "must" is the ability to adjust the height of your light. You need to keep the lamp about 4" above your seedlings to ensure that they get enough light. Otherwise, the plants may bolt and grow long and spindly. You will also need to move the light up as the plants grow.

There are many options for nutrient solutions. I get good results with Fox Farm Grow Big which is a commercially made organic plant food. Just dilute it with water according to the directions on the bottle. When you fill the reservoir, make a mark on the side and note how many gallons the reservoir holds. This will make mixing the nutrient solution easier in the future. I change my nutrient solution about once a month and I keep the reservoir topped off by adding water as the solution evaporates. You do not need to add more nutrients every time you top off. If you do add nutrients each time, you will likely over feed your plants and they may suffer as a result.

Plants grow best if the PH of the nutrient solution is maintained around a range of 5.5 to 6.5. You will need a PH test kit ant a way to adjust the PH up and down. Commercial products are available that contain buffered acid and base solutions for adjusting PH. You may also use vinegar and baking soda.

You should flood the growing bed with the nutrient solution once or twice per day depending on how well your growth media retains moisture. Plug the pump into the timer and set the pump to run for about 5 minutes once or twice per day. (5 minutes is usually the shortest time possible using a mechanical timer. If you are using a digital timer you may use less time. Just make sure that the pump runs long enough to fully flood the growing bed.) After the pump stops, the nutrient solution will slowly drain back through the pump and into the outer container.

You will have the best results if you do a bit of research on hydroponics. There is plenty of information available online and in your local library. (Yes, that big building with the books.) Have fun and happy growing!!

I made it at TechShop! www.techshop.ws