Will easily be the cheapest. however be prepared to put in considerable man hours. We did a 180 tank for my buddy with it, took roughly 6-8 hours of sand cleaning. It will stain the bucket/hands/whatever it touches. including the tank if not rinsed enough. Looks amazing. way heavier than normal sand. So it doesnt get kicked up into filters nearly as much. Imo it's the only way to go, if you're going for black sand. I'd be tempted to go black gravel though.jcardona1;2184084; said:you should look into the 3M Color Quartz sand. comes in lots of different colors. try your local pool stores to see if they can order it...
http://solutions.3m.com/wps/portal/3M/en_US/ColorQuartz/HomePage/Products/Crystals/