Aquaponic Gardening

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I'm researching expanded shale as a substrate for ebb & flow bed. Ebay has someone in Texas selling 100lbs for over $100 (incl. shipping). And in Utah. I've emailed them for an estimate. Is anyone in the PNW using/selling expanded shale?

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Keep checking hydroponic shops in your area, paying over a $1 a pound for shale is crazy, theres a shop in tucson here that sells 60 lbs for $20, can't imagine it would be too much more anywhere else since its not made here either.

Similar product on the east coast about $100 per ton.

Yes George but that figures you are going to pick it up at the rail yard yourself, not having it delivered in a plastic bag through the mail.

So the question is, can you go get the media yourself or have it delivered via dump truck or trailer to your home or do you need it delivered by shipping or freight on a pallet all wrapped in bags?  It will of course cost more if the people selling it have paid for it to be delivered to their place and then they bagged it and are selling it.  It will cost even more if the hydro shops is buying it from the above person who is selling it to them by the pallet since the freight shipping to the hydro shop is going to be figured into their price and the guy on e-bay probably go a deal on bags from a hydro shop somewhere and is trying to re-sell it him self.  $20 a bag retail is probably about right plus shipping.

Yes TCL, it doesn't always make sense.  Too, hauling and washing gravel is more fun in theory than in reality.  It's best looked back on as an experience you had once or twice.  Good luck Shannon.

TCLynx said:

Yes George but that figures you are going to pick it up at the rail yard yourself, not having it delivered in a plastic bag through the mail.

Yea, ya don't want to have to wash gravel all the time.  but I think if you set up the gravel washing work stations properly, it makes it much much much better.  I, all alone,can wash a ton (literally a ton) of brown river rock in under 4 hours if the work area is set up properly.

However, if your work station is not set up properly and you are bending your back at all while you swish the gravel in the bins of water.  You are gonna be aching and your rate of washing is going to deteriorate probably to the point that you can't even do it anymore by the 3rd day of half day gravel washing sessions.  Do whatever it takes to set up your washing bins so that as you swish a basket in the bin you will be standing with your back straight and your feet comfortably on the ground and your arms bent at a comfortable angle while holding the top of the basket under the water in the bin.  If you feel the urge to lean over while doing the swishing, the bin is probably too low.  I've made stands for gravel washing out of stacks of pallets or a pallet or boards on saw horses.  The height of your bins will affect what height "table" is appropriate.  And of course the height of the person doing the washing is the prime consideration.  When I did the "gravel washing party/workshop"  I set up 3 or more washing stations at different heights (different numbers of pallets under them) so that 3 people could be washing while three other people could be shoveling, three other people toting gravel to the washing stations, and three other people could be dumping gravel into the beds so that could keep up to 12 people busy and get the whole project done fast provided all the plumbing and other things are taken care of ahead of time.

I just got off the phone with the sales rep from Stalite.  Extremely nice woman named Debbie Stringer.  She quoted me $62 for a ton IF I pick it up.  The plant is located in North Carolina so it would be about a three hour drive each way.      If I want it delivered they'd have to put it in  a giant sack and the cost would then be around $150 plus shipping.  She's dealt with  a few of the members here and had nothing but wonderful things to say.


I told her about the community and she said she was going to join so we'll have a source right here.

If anyone wants her contact details let me know.

Yes, the Stalite (expanded slate instead of shale) is good stuff.  I've only been able to get the 1/2" stuff though I would love to try out some 3/4" but it isn't available close enough to me.  I have to pick it up at a rail yard here so the total cost is a bit higher for me.

I will recommend that people plan on giving a little acid rinse to the stalite after the normal washing/sifting.  This is because they use hydrated lime in the kiln process and simply rinsing it probably won't completely neutralize the alkalinity in the dust.  Once the media has settled in there isn't a problem with high pH but if you were to put brand new stalite into a bed and just hook it up to a system the pH will initially be way high.  For the stuff I used at the old place I simply added muratic acid to a tub of water to get the pH down below 6 and I let the stalite soak in that for a while before hooking it up to the system.  Here at the new place I'm letting the rinsed Stalite soak in rain water until I am ready to put it in the grow beds.

Strange thing about my stalite is the PH has been around 6.8 for months now with no adjustment whatsoever.  Maybe it is because of the rainwater tank top offs but I don't know.  Ammonia usually runs .25 and nitrite 0 so I'm happy with it.  I'd rather have had 3/4 but the 1/2 has been no problem thus far - no clogging.  However, I will add that I graded out a lot of fines from the 1/2 inch and I mean a lot.  It took over 2 1/2 tons to fill six 100 gallon grow beds.  I need a little more now due to settling.

With 3/4, you shouldn't have the problem with fines and you'd have a great media. 


Bobby, find out how much the shipping is by the ton - probably a lot and it might be a lot cheaper to rent a truck big enough to do it in one trip. 

Here's a question, my prospective supplier for expanded shale told me the pH is around 8.5, should I give it an acid/water soak? If so, for how long?  I can get 2000lb super bags for $400 and will likely pick up a couple  of them for that price. It's 1/2" down to 3/8". Kinda small, but river rock is hard to find and hydroton is non existent, and I want to build a larger project.

Has anyone ever used expanded shale concrete for building DWR troughs?

Ian, I don't really have experience with the shale so much but I would probably say give it an acidic rinse perhaps for several hours or let it soak overnight and then drain to waste before re-filling with fresh water.

But as I said, I'm just kinda guessing here.  I know there are media that are sold for hydroponics that have the same situation where you should soak it in water that has been adjusted down to a pH of 5 and they usually say soak overnight.

Thanks TC. Well, it looks as if I'm going to be writing about the experience. I'm picking it up next week. I've read somewhere about using volcanic cinder  as a medium in net pots, I wonder if one could use shale crush instead? I plan on building a  (6')short DWR and expand on the media bed system for the indoor winter season. My little community is telling me that if things go well until next February (my cycled up anniversary), then we will build a cooperative based community sized setup. That's what I get for opening my mouth and promoting the heck out aquaponics....guinea pig  until proven successful. Ha, Loving it! 3rd crop of Swiss chard and spinach ready to be picked. Its given away to the elders and single parents as part of our healthy community and bountiful harvest program.

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