Backyard Aquaponics
A place to discuss aquaponics

I'm going to add wicking bed next, but I have a very basic question. As the water level in the reservoir falls away from the shade cloth, how does it get from, say, half way down the rock filled reservoir all the way up to the shade cloth to continue to wick into the soil? It seems that as soon as the surface of the water falls away from contact with the shade cloth, the wicking would stop.

It would have to wick through the rock - this is the reason large rocks are not great for the media in wicking beds.

There is also a theory it evaporates and condenses on the soil layer. I build my wicking beds with sections of the soil going lower into the reservoir and use sand and plastics containers to make air voids over the water. I'm not convinced much 'wicking media' is needed if you have a plastic crate for the reservoir with the soil on top and round the sides.

I made some small wicking beds to test continuous subsurface flow (like Earthan beds). Basically a 55 gallon barrel cut in half, filled halfway with lava rock, covered in landscape cloth, then soil. Water enters near the top of the rock and a stand pipe keeps the water level about an inch or so below the cloth (I didn't want to disturb the bottom too much, in case particles were coming through). It seems to keep the soil damp a few inches down, but fairly dry on top, which I would characterize as successful, even with the large size of the rocks.

Expanded clay (hydroton, etc) is one media type specifically noted for its "wicking" properties. I think mattyoga's suggestion is probably the more cost-effective though.

Bit of wicking bed info read from here on
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