Friday, July 6, 2012

Tanks and Grow Media

If I only knew then what I know now...

I like these troughs I found at Tractor Supply.  They are a bit shallow, but I think they will do very well.
Here's an update to my expansion using bunk feeders.
I'm seriously considering this long one (approximately 10"Dx24"Wx108"L) for a grow bed.  $154.00

These would make a nice fish tank.  The big one is about 300 gallons. 5'Dx3'H  $250.00

After building my own tanks from both 45mil EPDM and the pond liner they sell at Home Depot I would lean toward these heavy duty Rubbermaid Structural Foam Stock Tanks, because they are less likely to leak, easy to clean, easy to insert bulkheads into

I have also built an IBC system.  But polyethylene is not UV proof.  This round tank appeals to me because it would be less difficult to manage than a 4' deep IBC fish tank.   

My relentless quest for a reasonably priced media has finally turned up Pumice.

UPDATE 12/3/2012
Pumice has turned out to be a great media for net pots, but it packs, and I believe it would tend to clog if used in an aquaponic media bed where the purpose of a media bed is to filter the solids.  It might be acceptable in a hydroponic or bioponic system where solids are not an issue.

The pumice I bought looks exactly as in the picture.
The size ranges from about  3-8 mm.
The pieces are very hard and do not easily crush.

I crushed a piece with a pair of pliers.  Then I rubbed it between my hands.  Some particles first appeared to be long and pointed, but the rubbing caused them all to break down into irregular grit.  There were no sharp shards left in my hands afterward, and nothing that looked sharp remained.  It tends to form roundish particles.

It's extremely easy on the hands.  It's soft on the skin and nails; not at all like feather rocks or lava rock.  There are no shape shards, and if it brakes I doubt that it would create sharp shards. When it was dry it felt like placing my hands in puffed rice.
The best description I can think of is 'like heavy Perlite'

After soaking for approximately 20 hours about 2/3 sank and the other 1/3 remained floating.  It was easy to separate the sinkers from the floaters.
After two days 95% had sunk and eventually all of it sank.
I would suggest rinsing well as the water was a bit cloudy.

When I rinsed it, the first water changed from pH from 8 to 6.6, but after several rinses the pH did not change.  
The cost was $28 per 1/2 yard.

I would assume that it is available at many garden nursery suppliers so availability is less of a problem than expanded shale, and yet the price is well below clay medias.

Overall I think it would be a very good media for ebb and flow if some protection were put in place to screen the very small particles.
The material could be separated according to size with a screen, but it packs well enough that it does not fall through the cracks of a net pot like the clay balls, and yet continues to drain well allowing for plenty of air.

I'm very impressed by it, and look forward to replacing all of my other medias including Hydroton.  Considering the price it is well worth taking a look at.

The pumice worked in a net pot.  Fewer grains fell through the pot than if I had used Hydroton.

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