Media Bed Design Options

[downplay]

I've been thinking about ways to buy less grow bed material
and keep the media simpler and/or lighter. Do people do layered
designs? That is, how about placing a screen X inches above the
bottom, then a layer of mat/foam media, then topped with a light
material like hydroton or expanded shale?

This way, there would be very high biological surface area in the
mat/foam, and there wouldn't be so much aggregate media to
buy, maintain, etc. The roots could just hang in water-filled space
below the foam.

And, what of irrigation. I'd like to water them under pressure. Is it
reasonable to water a media bed using runners off a poly pipe
like some people do with foam filled towers? It seems I'd just need
enough little feeder lines to achieve the desired GPH.

As for the siphon drain system, I was thinking of having the siphon
or flout in a small separate box connected low in the bed with a
removable grate and/or filter so I just have to clean that periodically
instead of having to remove the siphon/flout.

What do you think? Bad ideas? Are there highly preferred alternatives?

[Jason]

I have not head of anyone layering the beds with different material, but I would assume that it could be done. Might make clean up between use a little more labor intensive as you would have sort out the materials for cleaning. Not sure about the "mat/foam" as the roots would clog the foam.

I have been looking at different siphon systems as well and kind of like the idea of the external drain systems like an external loop siphon does seem simple and you idea of the filter should work well as long as there is a gap before the drain. I am thinking it comes down to preference and what works for you. Give one a try and let us know what you find. i will do the same.

Jason

[downplay]

I have not head of anyone layering the beds with different material

I know people have layered aggregate type materials with good success. What I haven't heard of is foam in a horizontal bed or an intentional empty space.

But, there are plenty of people out there growing in pure foam with no other medium. Check out Bright Agrotech's Zipgrow towers or look on Youtube for Larry Athey's homemade vertical towers.

The empty space is not crazy either. I've already had it in a system that was unintentional. The roots that grew through the holes in the top bucket into the bottom drain bucket were always bright white, happy and healthy. They were mostly hanging in air during the drain cycle with a tiny bit of nutrient solution at the bottom of the bucket below the drain level.

I might even be able to get away without the hydroton layer on top but a dry layer is suggested to avoid algae growth. The algae could be blocked with plastic but at least hydroton is reusable and potentially multi-purpose. Also, it will give good shade to the foam layer so any worms won't have to flee the light.