A few centuries ago, the only way you could grow a plant without a soilless base was to suspend it over a pool of water mixed with nutrients, that would act as the feeding grounds replacing the earth's diet. Nowadays, we have wick systems, ebb and flows, drips, aeroponics, the nutrient film technique and many more, which only shows how far in this field we have gone. And because the offer is often so varied, it's confusing for the newcomer hydroponic gardener. Picking the right hydroponic systems is a tough job, so here are a little tips to help you know the difference:
Wick Hydroponic Systems
The wick system operates under very simple parameters, in that it's passive, with no moving parts attached to it. A wick is used to draw nutrients from the reservoir and into the growth tray and it's a fully automated procedure that takes little effort from you.
Water Culture Hydroponic Systems
Like I said in the introduction, the water culture was the first type of system invented in hydroponics. It stands on fairly straightforward principles: a reservoir filled with nutrient solution, atop of which the gardener places a floating platform that can hold several planters (or cups, or something similar). The roots of the plant that you "install" will be drowned in the nutrient solution, with the rest of the plant being held by the planters.
Drip and Ebb and Flow Hydroponic Systems
Ebb and flow hydroponic systems can be found everywhere and together with their younger brother, the drip system, they make up the majority of hydroponic gardens in the World. Both types of systems work on basically the same principles: a growth tray is attached atop a nutrient container. Nutrients are flooded into the growth tray by a pump, they are absorbed by the plants and the excess solution that couldn't be absorbed is drained down into the nutrient container, recycling it for future use.
Nutrient Film Technique Hydroponic Systems
Another popular hydroponic system, the NFT uses a constant flow of nutrients to wash out the plants' roots, feeding them in the process. Because this system uses no growth media for the roots, it allows for better oxygenation and it has low maintenance costs in the long run. Just like the ebb and flow or drip systems, the nutrient film technique floods the growth tray (where the plants' roots are dangling in) then drains the excess back to the reservoir. Like with the above mentioned hydroponic systems, this kind of nutrient recycling is a great way to save nutrients, but unfortunately it also creates pH instability in the reservoir, which leads to more complicated problems later on.
Aeroponic Systems
Although not hydroponic systems per se, aeroponics use some of the basic principles in water-based soilless plant growth, but use air vapors instead. Plants are usually suspended on top of a reservoir in aeroponic systems, with the container being tightly sealed. A mechanism creates vapors out of nutrient solution and sprays the result in the reservoir, engulfing the dangling plant roots. This helps them acquire nutrients faster but also allows for some great oxygenation capabilities, which cause your plant to grow heavily.