I did the same thing over the last couple of days with my 12g. A local pool supply company sold me a 50lb bag of filter sand for $7. (too bad I only needed about 10lbs of it!) I put my fish, filter, decor, plants, and siphoned water into a rubbermaid tub as suggested in another thread. It worked great as a temporary aquarium! I took all my old colored gravel and put it into three bags made from nylon hose. After rinsing out the pool filter sand (I used a 5g bucket and sprayed/overflowed water till it ran clear) I put it in the bottom of the tank and slowly added everything back in. I put the three bags of old gravel back in the tank and let it sit overnight. Everything was good this morning when I checked parameters, so I took one of the old bags of gravel out. I'll do this over the next few days as long as my levels stay the same. I really like the way the filter sand looks. And it has larger grains, so they don't suspend in the water very long at all. Water was crystal clear after the first hour!
BTW, I saw something cool at Walmart last night... Crayola (as in crayons) play sand. This may be old news to everybody else, but I'd never seen it before. They had all kinds of colors. I didn't get a price because it wasn't marked and I was in a hurry. It looked like a neat idea, but I prefer the natural look of the filter sand.
