Frequently Asked Questions

 Frequently Asked Questions

Expanded Shale

Should I wash the Expanded Shale before installing it in my system?
   We recommend that you wash it first.  During the manufacturing process, the majority of the fines less than 1/2" (13mm) are removed.  There can still be some fines left in the media along with some residual dust.
 
What's the best way to wash Expanded Shale?
   Many people will fill their grow beds with the Expanded Shale, disconnect the drain from the rest of the system, then flood & drain the grow bed once or twice.  In our test system, we just dump the Expanded Shale into a wheelbarrow, fill it with water, then shovel the shale directly into the grow beds.  We then dump the wheelbarrow through a 3/8" screen to catch the larger pieces and repeat the process.  For smaller amounts (to fill net pots), you can fill a 5 gallon bucket with shale and water and scoop the shale up with your hands or a trowel.
 
I have read that Expanded Shale is not pH neutral.  Is this true?
   Expanded Shale is a silicon-based material that is pH neutral.  The heating process in the kiln creates calcium and magnesium oxides on the surface of the material which can generate an alkaline pH.  Simply washing the material prior to use will remove the oxidized dust.  A report by Texas A&M University Research and Extension Center pubished an article in "HortTechnology" in October 2002 about the chemical properties of Expanded Shale and the effects it would have on clay soils as an additive.  They state that "[Expanded Shale] will not measurably affect the pH of neutral or calcareous soils".
 
Can I plant seeds directly in Expanded Shale or do I always have to transplant seedlings into it? Click to Enlarge
   Seeds can be planted directly in the Expanded Shale just like conventional soil.  Since the shale is more coarse than soil, we recommend when using small seeds, such as lettuce, to sprinkle them over the media, then wipe your hand over the shale to get them to fall between the stones.  Until the seeds germinate, it is best to raise the flood level or water frequently to keep the upper layer of the shale moist.  This picture is a lettuce seedling that has recently sprouted.
 
Where do I purchase Expanded Shale?
   Our products can be purchased through one of our reseller partners.  They will provide a quality service to you by insuring you have all the necessary components for your growing needs.  We will then ship the product directly to you!  For a listing of some our partners, please click here.
 
I currently use expanded clay pellets (Hydroton). Can I mix Expanded Shale with it?
   Hydroton and Expanded Shale can be mixed together without any issues. Expanded Shale can also be added to existing stone systems, which will help to increase the moisture retention in the grow bed.
 
How much does Expanded Shale weigh?  Will it float?
   Depending on the moisture content, Expanded Shale weighs around 1.7 pounds per liter (0.77kg/liter) when dry.  Because of its porous nature, a very small percentage will float.  Eventually these pieces will become water-logged and sink.  There have not been any reported problems with grow beds "floating" when flooded since there are so few pieces that actually float.
 
What else is it used for?
   Many people use Expanded Shale for growing orchids. Other people have told us that they used it as a biofilter in their outdoor water gardens or koi ponds.
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