# Expanded shale as substrate?



## Michael (Jul 20, 2010)

Hello everyone,

After 6 months of trying, I am finally registered on APC!

Has anyone used expanded shale as a substrate? I am giving it a little test by setting up two El Natural bowls with the same plants and mineralized compost. One has fine sand over the soil, and one has expanded shale.

The bowls have been set up for about 3 weeks with good results in both. The expanded shale bowl has a little more algae, but that may be due to the fauna (N. heteropoda) not eating the agae as fast as in the other bowl (Gambusia affinis).

--Michael


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## Seattle_Aquarist (Mar 7, 2008)

Hi Michael,

Welcome to APC! Sorry you had problems with the registration, I am glad that Cavan and Dave were able to get things resolved. I am glad you joined us!


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## jclee (Aug 24, 2009)

By expanded shale, do you mean vermiculite? Isn't that fairly buoyant?


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## Michael (Jul 20, 2010)

Hi Iclee,

No its not vermiculite, although it is made by a similar process. It is natural shale that is heated in a kiln until it "pops" like popcorn. The result is a 3mm to 9mm gravel that is lighter than normal aquarium gravel but still heavy enough to hold plants in place. It is used to improve clay soils in gardens, and like gravel or sand it does not break down.

According to the manufacturer, it is pH neutral and chemically inert. It is also very porous, which gives lots of surface area for beneficial bacteria. So far it is working well in the shrimp bowl, now 4 weeks old.

--Michael


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## Michael (Jul 20, 2010)

One month report:

All the flora and fauna in the bowls are doing well. Almost all the shrimp have molted.

Both bowls developed some hair algae. This cleared within two weeks from the expanded shale bowl, but has persisted in the sand bowl. I hesitate to attribute this to the expanded shale, but can't come up with another explanation. The water is very clear in both bowls.

Changing subjects a little, on a whim I bought some "feeder" ghost shrimp and put a few in the sand bowl with the gambusia (no other shrimp). I got two surprises. First, they ate the pond snails! The snails were literally crawling out of the bowl to escape them. Second, only one ghost shrimp died. After reading that most feeder shrimp die rapidly from poor conditions during shipped and at the dealer, I expected a much higher mortality rate.

--Michael


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## Tex Gal (Nov 1, 2007)

Can you post a px of this substrate? I'd like to see what it looks like.


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## Michael (Jul 20, 2010)

If I've done this correctly, there should be 5 photos:

1. A close up of the ES in the shrimp bowl, excuse the distortion
2. ES dry (and a little dirty) with a dime for scale
3. ES wet
4. ES wet close up
5. Both shrimp bowls on my desk. The window faces NW, and this is the only light source. In the winter I will need to use artificial light.

--Michael


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## Michael (Jul 20, 2010)

The bowl with the sand cap collapsed!

Almost simultaneously (within 12 hrs) there was a die-off of previously healthy ghost shrimp, a diatom bloom, and big bubbles out of the substrate. I could not smell anything when I tore the bowl down, so maybe the bubbles were CO2.

The gambusia survived, but those are famous for surviving terrible water conditions.

So what caused it? Overstocking? Anaerobic substrate? Sudden illness in the shrimp that caused the die-off and fouled the water? The sand? I did notice that the hair grass had lost most of its roots, but the Egeria roots still looked healthy.

Meanwhile the expanded shale bowl perks along with no problems.

I've re-started the bowl using mineralized top soil with expanded shale cap. The plants were rinsed and but back in. The two surviving ghost shrimp and the gambusia went into one of the ponds--they've made their contribution to science, LOL.

--Michael


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## mossback (Aug 12, 2010)

Michael, is your substrate Permatill ?


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## Michael (Jul 20, 2010)

I don't know that name--is it a brand? The ES I usually buy is sold bagged at Calloway's Nursery (a chain in Texas) and is made by Tru-Gro. Here is their description: http://www.earthspride.com/Index.htm#EXPANDED_SHALE0 Cost is about $12 for 40 lb.

It is also available in bulk from stone and landscape material supply companies for $63 per cubic yard.

I haven't been able to find any information on its CEC.

--Michael


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## Michael (Jul 20, 2010)

Did some deep search on Google, and found this:
http://www.organicminedminerals.com/PDF File/Soil amendment.PDF

Look at page 4, first full paragraph. Answers my question about CEC (none), and also says that calcium and magnesium oxides will result in high pH. This is directly contrary to what a company rep told me in person. (Surpirse, surprise!) But it also says that there is very low calcium carbonate equivalent so it should not affect pH in neutral or alkaline soils.

Wonder what it does in water?! My shrimp are still alive, I guess I need to take a sample into the LFS for a test.

--Michael


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## Tex Gal (Nov 1, 2007)

That is interesting. Their site says it can absorb and release nutrients so it sounds like it has a high CEC rate. It also says it's inert so it certainly can't hurt anything. 

"is chemically inert and completely inorganic. As a result, it will not compress, decompose or react with other agricultural or horticultural chemicals. ...expanded shale is able to absorb and release water and nutrients, which may increase the nutrient protection capacity of a highly porous growing medium."

I wonder who you believe. It would be easy enough with regular water changes to see it your water becomes harder. Perhaps there are different kinds of expanded shale.


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## mossback (Aug 12, 2010)

But saying that it has negligible CEC is pretty definitive. So I would interpret the bit about absorbing and releasing water and nutrients as meaning that when the surrounding soil gets wet, a TruGro granule will absorb some of the water, including nutrients dissolved in it. And when the surrounding soil dries out, plant roots will gladly suck water and nutrients out of the TruGro. 

With the caveat that I have no experience whatsoever with expanded shales (I am currently experimenting with Turface, so I like to learn about alternatives) here's a wild guess as to what TruGro will do to your water parameters: being essentially inert and having negligible CEC, nothing. But it would be interesting to know what the LFS says.


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## Michael (Jul 20, 2010)

In past conversations with the author of the second article, he said that it is the porosity of ES that enables it to store and release water and nutrients to plant roots. This is in contrast to gravel or sand as soil amendments. Typical quartz sand is not porous, and holds a relatively small film of water on each particle by surface tension.

This porous nature of ES was one of the reasons it sounded like a good candidate for substrate: lots of places for beneficial bacteria.

I'll try to get some water tests.

--Michael


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## Michael (Jul 20, 2010)

Water test results follow.

Reference sample:
pH 8.0
KH 9
Nitrate 5

Shrimp bowl with ES:
pH 7.8
KH 12
Ammonia trace
Nitrite 0
Nitrate trace

I should explain that the reference sample is from my pond. When I set up the shrimp bowls, I decided to fill them with pond water, rather than conditioned tap water. I have continued to use pond water for topping up and water changes. My reasoning was that I KNEW the pond water was safe since I have healthy fish and plants growing in it, and our tap water has notoriously variable chemistry.

So can we conclude that the ES is harmless, if not benenficial?


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## chuckgoecke (Dec 20, 2010)

Hi Michael, etal
I'm new here, and found this site looking for more info about using expanded shale(ES) in aquatic situations. First off, I'm from North Dallas myself(Plano) and have been an on-again off-again aquarist for decades, plus I have lots of experience with aquatic plants in pond settings. I was a horticulturist at North Haven Gardens for 10 years, where amongst many areas of responsibility, I ordered the pond plants and supplies(admittedly not a big line at NHG), also assisting customers in these areas. 

I'm somewhat surprised that the company that makes the ES (TXI in Midlothian) hasn't tried to research or promote its use as a pond/aquarium filter medium and gravel substitute. It seems to me to be ideal for this, not only because the stuff is 8.99 for a 40 lb(.9 cuft) bag at the Plano feed store(Wells Bros), but because of the high porosity, high effective surface area, and other things that one wants in a filter media. 

(edit)I use expanded shale for both a substrate and a filter medium. I'll discuss the plants and usages below.

The biggest issue I've seen with the stuff is that it has a rather sharp alkaline reaction, but this is easily solved by washing it with acid. When I pH tested ES myself, by soaking a one half Styrofoam coffee cup of ES and filled with distilled water, the pH tested off the scale of the Bromethyl blue test, in other words, well over pH 8. I washed the ES in a five gallon pail, first with tap water, then I added about 1/2 cup of concentrated sulfuric acid(from the plumbing dept at Home Depot), mixed it well with a clean wood stick and let it sit for a couple days. (I carefully dilute the acid into about a quart of water first - this is ABSOLUTELY CRITICAL THAT YOU ADD ACID TO THE WATER, as it heats up a lot and could boil into your face if done vica versa). At first it fizzes at lot but calms down soon and when I tested the water standing over the ES after a couple days it was back up to near 8 again. I suspect that all the lime in 20 lbs of ES easily sucked up that much acid, but I didn't feel like titrating the amount of acid to completely dissolve all the free lime in the shale. I think next time I do this, I'll try pool acid(hydrochloric acid) or even (lots of)vinegar as they somewhat safer if used outside with good ventilation and probably even better at dissolving the excess calcium out of the ES. 

Of course you want to be sure to pour off the acid wash residue, which I just did into the middle of our grass-free back yard(thanks to the shade and our pet tortoise) away from the big trees' roots. Then wash it again very well with tap water. I then let it age and stabilize for a few more days. The final pH with distilled water was about 7.8, which I considered good enough, as our tap water here is about 8. Besides getting rid of any excess alkalinity(which probably would happen anyway in a few weeks with water changes), the acid wash undoubtedly increases the porosity, permeability and effective surface area. 

Now that I've had plants and fish in the Pond(its a 400 gallon rectangular above ground in my greenhouse - primary purpose is heat storage) for about a month, after a month of stabilizing, I've had no problems. I have rosy reds, White clouds, Paradise Gouramis, goldfish and Koi, all young, and doing great. The plants are one crypto(which I'm curious how it will deal with the cool water(it has gotten as low as 58degF), several Umbrella papyrus, several colocasias(mini taro tubers from the market), a compact Syngonium, plus a bunch of veggies that I either cut or putted up when the first frost was predicted a few weeks ago. The tomatoes, which were just cuttings have finished ripening the green ones but have set no more and seem to be slowly dying; the jalapeno plant is looking great, but hasn't set any new fruit; the Chili Piquin cuttings ripened their green fruits, but I haven't checked to see if they are actually rooting into the ES like the tomatoes. These plants are in three different situations. The crypto is under water, the Umbrella and taros are emergent, and the other plants and veggie cuttings are in the wet-dry spray filter over one side of the pond tank. I wasn't sure if there would be problems with acid treated ES, if the acid(basically drain opener) would have any toxic additives, or if the reaction of the acid with the shale would release anything nasty. I would have to say no on all accounts.


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## Michael (Jul 20, 2010)

Hi Chuck,

Very interesting! Since my first tests with the shrimp bowls were successful, I went on to use an ES cap in a 20 and a 10 g tank. You can read a journal about the 20 at http://www.aquaticplantcentral.com/forumapc/el-natural/

I always soak and rinse the ES very thoroughly before it goes in the tanks, but never measured pH or did any acid treatment. When the 20 was first set up, the pH was 7.8, then declined to 7.4-7.6, where it has been stable for 4 months.

The tank has done very well, with good plant growth and no problems to speak of. An advantage of the ES is the large particle size--mulm does not collect on the surface, but settles about 1/4" to 1/2" below the surface of the ES, just in the right level to remain aerobic and be used by plants.

I've also used ES as the sole medium for emersed aquatic plants in my ponds with good results.

Join us over at the DFW Aquatic Plant Club forum on this site--just look at the idex to find it.

--Michael


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