The tank or container should be watertight to conserve the nutrient solution. Construction materials will depend upon the size of tank or container. Large tanks can be built of wood, asphalt paper, concrete, or metal. The wood should be free of knots, and cracks should be sealed against leakage with asphalt. Asphalt paper can be used with wood framing to make a workable tank. A metal tank should be painted on the inside with an asphalt-base paint.
Metal, earthen, and glass containers can be used quite successfully for a small-scale operation. Ground beds, flower pots, baskets, and even bean hampers have been used in aggregate culture. Since they are not watertight, however, some of the solution is lost. Metal containers should be painted on the inside with an asphalt paint, and glass containers should be painted on the outside with a dark-colored paint.
The aggregate material may differ greatly in composition. Well-washed silica sand makes one of the better materials. But any sand, preferably of coarse texture, that does not contain lime may be used. Sand is a desirable medium because of its ability to hold moisture, and because plants may be easily transplanted to it. A mixture of sand and gravel makes a very good medium if the sand or gravel does not contain much lime. Well-washed cinders may be used, provided that they are not high in toxic materials. Other materials such as peat moss, vermiculite, wood shavings, etc. are also satisfactory. You can obtain aggregate materials from local lumber yards, garden centers, or garden-supply houses.
from: http://plantanswers.tamu.edu
Materials and Equipment
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