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Growing plants hydroponically using aggregates such as sand or gravel is sometimes preferred to the aquaculture method as the aggregate helps to support the roots. The aggregate is also held in the same kind of tank that is used for a water culture hydroponic system. The solution of nutrients is held in a completely separate tank and is pumped into the aggregate tank to moisten the roots as needed.
After the aggregate material has been flooded it is then drained to provide aeration. Enough water and nutrients are meant to cling to the aggregate and roots to supply the plant until the next flooding of nutrients.
The nutrient solution is generally pumped to within about an inch of the surface and is then allowed to drain. If the top surface of the medium bed is kept dry, then the growth of algae should be kept minimal. To allow for rapid drainage, the aggregate must be very coarse. Use sand with particles at least 1/16-inch diameter or perhaps gravel of about 1/4- to 3/8-inch diameter. The best aggregates tend to be silica gravel, granite, basalt, or smooth river-bottom rock of the inert type that has no calcium in it.
Larger aggregates will always require more frequent flooding, whereas the smaller aggregates tend not to drain properly. In smaller, experimental units you may use any of several different substances. Perlite, Styrofoam, and even crushed marbles have all been used successfully by hydroponic systems hobbyists. The aggregate should be flooded for about 10 minutes and then allowed to drain for no longer than half an hour. | 
