Is this coral sand?

[Siput]

Hi, my friend recently passed me a bucket of very white sand which the LFS had told him it was crushed coral sand. The grade of this sand is like no. 0 sand except that it is very white, almost like bleached coral, and in fact looks like crystalline salt. The LFS had told him this was pure crushed coral and that over time it will take on a very beautiful, slightly reddish-brown hue.

Question, has anyone come across such sand before? Is it really crushed coral (dazzling white, almost!), and is it safe for my new tank?

Plan to put in 2" "normal" grade 0 coral sand and a tidy (netting), followed by 2"-3" of this stuff for my DSB...if this is not coral sand, will the below 2" of normal coral sand still be able to buffer/function in its capacity of a DSB?

Many thanks for any and all advice given!

[Michael Young]

Nobody will no for sure even when looking at the sand physically. You really need a lab test to know what it really is. My policy: If in doubt, don't do it.

[Achilles Tang]

If its coral sand ie. calcium carbonate-based.... do the vinegar test.

If it bubbles and dissolves.... it's coral sand.

If it doesn't... it's probably mineral-based sand like quartz or silica.

[Siput]

HI AT and MY, many thanks for the advice! Will do the vinegar test as suggested this morning!