Coal Slag blasting sand for substrate

[kidbookrev]

Hi,

I would like to use sand that I can get at my local hardware store. All they have for playsand is regular tan. However, I would really like to use black sand. The only black sand they have is blasting sand. It is labeled as coal slag, washed in freshwater, and "Safe to Use", whatever that means.

Will this be safe for use in a tropical aquarium?

Isaac

[mike47517]

Welcome to the sight!!!
I would think it would be fine but just to make sure put it in a empty tank that is cycled and check the water to make sure it is safe for a couple days. if so then yes it will be fine.

[JasonC]

Okay, so not knowing what coal slag was, I looked up the MSDS (Material Safety Data Sheet) for a couple of brands of the stuff.

Found that most have chemicals like Silicon Dioxide, Aluminum Oxide (up to 25%), Iron Oxide (up to 31%), Calcium Oxide, Magnesium Oxide, Potassium Oxide, and Titanium Oxide in them.

While I cant profess to know what is safe or not for a fish, I can say seeing chemicals like iron, calcium and potassium in a product would give me pause as those are chemicals that people are always finding causing them problems in high ammounts in their tanks.

It would be interesting to see how much of those minerals would actually leach into the water though... I would tread carefully if you decide to proceed.

Hopefully someone will chime in that has real world experience with the product!

[Algenco]

I too would be concerned with the minerals in coal slag.
Do you have a pool company near by? ask them to order a bag of #M color quartz grade T in black

[jsoong]

I would also be wary of using non-inert substrate. Although the list of oxides listed by Jason are non-toxic, some might give you problems. Eg Iron oxide - rust - will get into the water. High iron might get you into algae problems, plus it will stain your tank orange. The Silicates might get you into diatoms.

The other concern is blasting sand is sharp & will be unsuitable to fish that would root around in the substrate or those with fragile/long finnage.

[missileman]

I honestly don't know what chemicals or minerals might cause problems from coal slag but I do know that my local power company (coal burning) is building a new retention pond because of problems with mercury and other chemicals leaching from the capped coal slag pile into the ground water.

[gzeiger]

I've never used this product, but purely in terms of what I know about chemistry:

Silicon dioxide is quartz. It is completely insoluble, and not the same as the silicate jsoong mentioned. ALuminum, Magnesium and Titanium oxides are also insoluble.

Calcium oxide will dissolve somewhat. Calcium makes the water hard, which may or may not be good depending who lives in the tank. This will also tend to raise pH without adding any KH, so I would be careful of it for that reason. However, carbonate in the water would remain available as a buffer against acid formation, which is the normal concern in an aquarium.

Potassium oxide will dissolve for all practical purposes completely. It is a very strong base and will have a large and temporary effect on pH and is therefore unacceptable in a tank. Thorough rinsing should remove it.

That leaves the iron problem. Jsoong is correct about staining your tank orange, as well as about the algae and sharpness of the particles.

I wouldn't use it, as I don't think there is really a ready solution for the iron, even if you decided to go with all guppies or something that wouldn't care about edges. A pool/spa store like Algenco mentioned would be another good source of black sand, or a gardening store or nursery.