I'm going with Taihitain Moon Sand for the 180 setup. How many 20lb. bags do you think I would need for 1 1/2 inch layer. Pet Mountain has TMS on sale.
I've had it before on other setups and it's awesome. Colors pop off the sand, it doesn't get caught in HOBs if you run them. It's dense enough poo doesn't get under it and light enough to gravel vac with ease.