# Aquarium safe clays?



## lildark185 (Jul 7, 2006)

Is there any clay that will be safe for the aquarium?


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## northtexasfossilguy (Mar 6, 2009)

A) What do you want the clay for?

B) Clay is the watery form of the rock type known as shale or slate, so to get the same look you could use those rocks. The way to tell if its aquarium safe is to take a bottle of Hydrochloric acid, maybe 10% solution, and drop it on the clay to see if it fizzes. You could use vinegar but you might get false negatives as the acid in that is pretty weak. There are carbonate clays, which is what you are testing for with the acid, so be careful. They will be grey or whitish color, and the safer ones are red or black. All or most all clays will turn to mud over time when placed in water. Almost all of the aquarium fish come from areas in rivers that are usually clear, that means the bottom is made of rock, gravel, or sands, and those are the best types of rock to keep it clear.

Another caveat with clays are that they may contain heavy metals or chemicals if you just pull them out of the yard, and even some of the pottery clays.










This is what a local river near me (the Trinity) looks like, it runs through the "Eagle Ford" shale, and as you can see its as brown as a construction site porta-john.


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## lildark185 (Jul 7, 2006)

I wanted to make clay caves for my plecos.


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## northtexasfossilguy (Mar 6, 2009)

You could get some pottery clay and shape the caves for them, then bake it. Once it hardens it shouldn't be a problem in the water. Try and find a shop near you that does pottery and see how much that would cost you and for help with building it so it doesn't break on you.

The pleco's get large so keep that in mind also.


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