Pea gravel or aquarium rocks a 1/4 in. diameter works just fine in a dwc. Cut a small hole in the top of the lid so you can use a turkey baster to water the plants until the roots hit the water. Or you can have a higher water level, about 3/4 of the way up the pot and run it that way until the roots propagate down into the mix.

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"There's no money for your issues so long as we're squandering $50 Billion a year on the drug war"- Ben Masel