The deep water culture method, also known as the reservoir method, is one of the easiest of all the true hydroponics growing systems. A container holds about two inches of nutrient solution. Several plant containers sit down in the nutrient solution. An aquarium air pump constantly bubbles in the nutrient solution, keeping the plants roots from drowning.
Often, small holes are made around the bottom 2 inches of the plant pots, allowing the roots to grow out into the nutrient solution. As in the example above, an effort is usually made to keep light from getting to the nutrient solution.
Wherever there is light and nutrients, algae will grow. Algae eat the nutrients you are trying to feed to your plants, and when pieces of algae die they attract fungus gnats. Fungus gnats lead to many other problems.
Because of its simple design and simple function, the reservoir method is a good choice for homemade hydroponics. Since there are no drip or spray emitters to clog, it is also a good choice for organic hydroponics growing systems.
This system is well suited for volcanic lava chips media, or else a mixture of one part vermiculite to 5 parts expanded clay pellets. As with any hydroponics growing system, you will want to brush up on your hydroponics feeding tips before beginning.