What sand is this?

[SweaterVest]

Greetings all. I was given a 70g aquarium and I am setting it up as a reef tank. The aquarium was used previously with freshwater fish, and has an abundant amount of sand/substrate. However, I do not know what it is -- and the previous owner has forgotten/doesn't know either

It would be great to know what this substrate is, if it can (or should) be used in the new reef setup. Help?

 

[jda]

Pour an acid on it and see if it reacts? If not, then it is silica sand. It is safe to use and it will not release bad things into the water or anything, but you won't get all of the benefits of aragonite sand like being able to have sandbed creatures, buffering of pH and buffering of phosphate.

I would not use silica sand in a saltwater tank for these reasons.

If the sand is aragonite, pouring some vinegar on it will be similar to mixing vinegar with baking soda.

 

[Cell]

Looks something like Carib sea Natural Reef or Florida Crushed Coral

 

[SweaterVest]

Pour an acid on it and see if it reacts? If not, then it is silica sand. It is safe to use and it will not release bad things into the water or anything, but you won't get all of the benefits of aragonite sand like being able to have sandbed creatures, buffering of pH and buffering of phosphate.

I would not use silica sand in a saltwater tank for these reasons.

If the sand is aragonite, pouring some vinegar on it will be similar to mixing vinegar with baking soda.

I poured some vinegar on it and it reacted, frothed and bubbled up

Now I wonder what to do with this information, as I definitely want to use a proper substrate e.g. Aragonite that will have pH buffering and allow for sand-dwelling fish and inverts.

The particle size seems to be 0.5 - 2mm.

Visually it most resembles Caribsea Fiji Pink:

If there's silica in it -- would that be a problem?
..
Should I clean it and run with it?

 

[Floyd-]

Personally I would not risk it. Buy some new sand and have some piece of mind.

 

[jda]

If you want sandbed critters like gobies, cucumbers, etc. the grain size will likely need to be smaller than that, or at least mixed, Special grade reef sand is a good place to start.