Crushed substrate acting as refugium

[RavePartyReef]

I've always had small grain sand in my tanks for years and even though liked the natural look, when starting my current tank I switched to black sand. I got Hawaiian black sand(Caribsea) and at first noticing the grain size I was skeptical. It is sort of like crushed coral size, and I gave it a try anyways. I must say I am very pleased with it. The larger grain size makes siphoning the gravel a lot easier when doing periodic maintenance, and the cloudiness is minimal...so far after 6 months, my sand has been cleaned a couple of times and it is something i Hated to do while with white sand because of the mess it would cause to everything. Anyways, besides that I have noticed the amount of life that resides between the gravel grains....when looking closely, I see lots and lots of pods, and they move freely there without the fish eating them, similar to a refugium. Granted the five allows for macro and nutrient export, but as far as keeping pods, it does similar job...
The fish are always darting towards the gravel eating them, but they can survive without being completely eaten and thus serve that purpose...