Hydroponics
Hydroponics is the growing of plants without soil. There are a number of
technologies utilized in hydroponic systems, with a highly-varying degree of
technical sophistication. This page details a few of the systems I have built
over the years.
Deep Water Culture (DWC, or "Bubbler")
I have built more deep water culture systems than any other system,
probably because they are very simple, inexpensive, the parts are easy to find,
and they have worked well for me every time I have built them. They are
basically a container to hold the nutrient solution, some form of mechanical
support for the plants, an aquarium airstone to provide a constant stream of
bubbles to keep the solution moving and oxygenated, and an aquarium air pump
to provide air to the system.
This unit was built from a plastic storage bin with lid. The mesh baskets where
sourced from Amazon. The hole saw chosen to cut holes slightly smaller than
the lip of the basket. Each basket holds a peat pellet in which the seeds are
planted. The translucent plastic of the bin allows the level of the nutrient
solution to be monitored, however if you are placing this outdoors you might
want to use a bin that is light-proof to help control the growth of algae.
Here is the system up and running. The level of the nutrient solution is high
enough to reach the bottoms of the baskets and soak into the peat pellets.
The grow lights are on a 12 hour timer. For this run, I had a heating mat
under the bin and a slab of foam insulation under that, but this turned out
to be unnecessary, it would have been fine just under the lights.
As the plant roots grow down out of the peat pellets, the level of the
nutrient solution becomes less critical, as long as the roots are in the
solution and the solution stays aerated, it should be fine. Here the
system has a good batch of basil plants growing.
I have successfully grown basil, lettuce, and herbs with this setup indoors
during the winter months. I have also tried cherry tomatoes and peppers,
but those plants got 'leggy' due to the lack of sufficient light, and do
better outdoors.
Aeroponic/sprayer
Although this design is referred to as "aeroponic" in several places on
the web, a true aeroponic system uses high-pressure pumps and fine nozzles
to produce a mist of nutrients to cover the roots. This design uses a low-pressure
pump and sprayer head sold for ponds and fountains, which produce a coarse
spray. It also uses an aquarium airstone and pump to keep the nutrient
solution saturated with oxygen.
For this unit, I used a 5 gallon plastic bucket as the tank. A mesh lid was
purchased from Amazon, along with some clay pebbles (LECA) to hold peat
pellets upright. The pump and spray head were sourced from a garden center,
and an aquarium air pump and airstone from Walmart. I cut down a lid for
the bucket to serve as a base and mounted the pump and airstone to it via
zip-ties. This keeps the pump from falling over, and the airstone from
trying to float. I should also have included a depth gauge for the neutrient
solution (a clear plastic tube, elbow connector, and a grommit would do),
since it was difficult to determine how full the system was without it.
In operation, the pump sprays solution upwards against the bottom of the mesh
lid and media, keeping them wet but not submerged. The airstone provides
oxygen to the solution. The small plastic bin and brick to the right are a
rain shield for the air pump, since it is not water-proof. This unit was
used outdoors and produced two excellent crops of cherry tomatoes.
Nutrient Solution
For nutrient solution, in all cases I used 3-part solution by General Hydroponics,
ordered from Amazon. I used one tablespoon of each of the three parts to
one gallon of tap water. For topping off, I would use tap water for two
weeks, then a fill with solution, then tap water again, repeating until harvest.
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