This is something we've been calling "Oats Sand", a Helmeda sp. algae skeletal structure that forms dunes in low-energy areas on degraded Caribbean reefscapes. Apologies for the filthy glass. This is mostly the bigger frond'ed species (~1cm), big mystery-snail for scale. No idea where you might buy it these days - I had to lift-bag from 100' and it doesn't travel well, though it's pretty durable once established (this is 8~10yrs old including three house-moves). I saw it in the shops maybe 20yrs ago for marine set-ups, but few seem to recognize these days. It's near-pure CaCO3 so may lead to some surface crust & will hold your pH, so choose your stock & keep your levels steady.
With a little flow it stays bright-white & is pretty cool for burrowers, non-diggers or light diggers; however, big cichlids will grind it to powder within a couple of years - my big jag, for example. Otherwise the gaps are pretty open so it "breaths" without/with less gas pockets and eels, MTS, plants etc love it.
With a little flow it stays bright-white & is pretty cool for burrowers, non-diggers or light diggers; however, big cichlids will grind it to powder within a couple of years - my big jag, for example. Otherwise the gaps are pretty open so it "breaths" without/with less gas pockets and eels, MTS, plants etc love it.
