Black Sand - Is it ok to use or problematic?

[rkpetersen]

I'm setting up a new tank and thought I might use a black sand substrate; specifically, 40 lb of Carib-Sea black Hawaiian live sand. I would have just gone ahead without a second thought, but I recently saw a random comment on another thread here, which suggested that black sand might contain undetected pieces of metal. I didn't know what to make of this, but when I was getting the sand ready to use, I ran a few high power neodymium magnets through it, just to see what would happen. Much to my surprise, many or all of the black sand particles themselves seem to be quite magnetic! Here's one of the magnets, coated in clinging sand grains.

So, that's strange. Apparently black volcanic sand has a high iron content? Is there anything else to be concerned about? Any issues I should watch for as far as water chemistry?

 

[Crabs McJones]

I'm setting up a new tank and thought I might use a black sand substrate; specifically, 40 lb of Carib-Sea black Hawaiian live sand. I would have just gone ahead without a second thought, but I recently saw a random comment on another thread here, which suggested that black sand might contain undetected pieces of metal. I didn't know what to make of this, but when I was getting the sand ready to use, I ran a few high power neodymium magnets through it, just to see what would happen. Much to my surprise, many or all of the black sand particles themselves seem to be quite magnetic! Here's one of the magnets, coated in clinging sand grains.

So, that's strange. Apparently black volcanic sand has a high iron content? Is there anything else to be concerned about? Any issues I should watch for as far as water chemistry?

My uncle has the black sand in his tank, the tank is pushing 8 years old I believe, and no negative effects to speak of. :)

 

[themcfreak]

I went special grade in my newest build, but my last few have had that same exact sand. I never had any problems I could attribute to the sand at all. But just be aware, when using magnetic glass cleaners, little pieces can and will stick to the magnet and streak around with the cleaning apparatus. Never personally had that scratch the tank, because I would always stop (you can feel there is sand in it), but just be careful not to scratch everything :)

 

[rkpetersen]

But just be aware, when using magnetic glass cleaners, little pieces can and will stick to the magnet and streak around with the cleaning apparatus. Never personally had that scratch the tank, because I would always stop (you can feel there is sand in it), but just be careful not to scratch everything :)

That is a really really good point. This stuff is not only magnetic, it's mostly basalt, so it's going to be harder on average than white sand, much of which is softer aragonite. Dang, thank you so much! I use Flippers with abandon in the other tank, with no scratches, but there could be more danger with this sand.