Hydroponics Experiments

Anyone can build a simple, automated hydroponic system without spending a lot of money. This system is compact enough to fit on a kitchen windowsill-although it can easily be expanded to accommodate any growing plant collection. All the materials that are needed for this system can be found at discount superstores, aquarium supply stores, or hardware stores for under $25.

We used a 2-liter bottle for the nutrient reservoir and an ice cube holding bin for the plant trough. Once you comprehend the logistics, feel free to experiment with other containers. To prepare your nutrient reservoir, drill two holes in the cap of the 2-liter bottle. The holes should be just big enough to snugly hold the 1/4-inch straight through connectors. One hole will be for the water line and the other will be for the air line. Drill a hole in the side of the trough (the ice cube holding bin) as close to the bottom as possible. If you plan on expanding your system, drill another hole on the opposite side. Insert the straight through connectors in the drilled holes. Create a quality seal around the connectors with glue or silicon caulk.

Create your water distribution hose by drilling several small holes in a piece of irrigation tubing cut to fit the bottom of the trough. Connect one end of the tube to one of the fittings on the inside of the trough. The other end of the tube can be sealed with a dab of glue or caulk. If you plan on expanding your system, don't seal the other end. Instead, connect it to the other fitting on the opposite side of the trough. Connect the water line from the nutrient reservoir to the trough. Cut another piece of water line to about the same length as your nutrient reservoir. Then connect this line to the other side of the water line connector, on the inside of the bottle cap. The line should hang down to the bottom of the 2-liter bottle when the cap is on.

Run the air line from the air pump to the other straight through connector on the cap of the bottle. At some point in the air line, splice the line to put in the T connector. Off the T, connect the aquarium air line bleed valve.

Fill your 2-liter bottle with water until it's about three-quarters full. Reconnect it to your trough and place the trough where it will be situated. Turn on the air pump and close the air valve. The water will be pushed into the trough. Gradually ease open the valve until the water is moving into the trough very slowly. It's okay if it takes up to a half-hour for the air pump to push all the water out of the bottle.The goal here is to have the valve closed enough to allow adequate pressure to build inside the bottle to push the water out, but open enough to allow air to escape when the pump is off, so the water can flow back into the bottle.

Now you're ready to add the medium and plants. We found that expanded clay or lava rock works well. Any number of plants will work in this system. Succulent herbs, such as basil and mint, are particularly easy to grow.

If you want to expand your system, simply build another trough and attach the incoming water line of the new trough to the end of the previous trough. We found that up to two modules of this size could be powered from the same pump and nutrient bottle.

Flooding and draining the system once a day should be adequate. But if you're growing a large plant in a sunny location, you may have to set the system to flood and drain twice a day.

A hydroponics project doesn't need to be that expensive. The most expensive
part of a hydroponic experiment is the nutrient solution. You may be able to
make one from the chemicals which your chemistry teacher has on hand. A
Hoagland solution is a common solution used by plant scientists. A cheaper
alternative is to buy a premixed hydroponic fertilizer from a hydroponic
supplier. There are dozens of hydroponic suppliers on the internet. Homegrown
Hydroponics sells DNF which costs $11 for 500 ml, which would make 50 liters of
full strength nutrient solution. Fifty liters which would be plenty for most
hydroponic experiments and it is often possible to use half-strength solutions.

Hydroponics reservoirs can be made from plastic food containers, such as 2-liter
soda bottles or even 35-mm film cans. An aquarium air pump, tubing and valves
are useful to provide aeration but not absolutely necessary. My book has
instructions for several hydroponic experiments and constructing inexpensive
hydroponic equipment.

There are all sorts of hydroponic experiments. Some examples are:

1. Compare plant growth in water to that in a hydroponic solution.

2. Compare hydroponic solution with a fertilizer like Miracle-Gro.

3. Effects of solution aeration of plant growth.

4. Effects of root pruning on plant growth.

5. Plant effects on the nutrient solution pH.

6. Nutrient solution pH effects on plant growth.

7. Nutrient solution salinity effects on plant growth.

8. Effects of adding plant hormones to nutrient solution.

9. Can fish wastes supply nutrients for plant growth?

10. Examine mineral nutrient deficiency or toxicity symptoms.