I have a new tank set up with dry sand in it. I have never bought dry sand before, and I wanted to know if I will ever get all the same sand critters as I would with live sand. Do I have to add it myself? The sand in the tank is about 4in, and the refugium sand is about 6in. It's been about 2 months and I still dont see any activity in the sand, but everything else is perfect. So what do I do?