I have estes marine (safe for fresh and salt water) sand. It is available in many colors, although it is a bit pricey (about $1/pound). It took 25 lbs to put a roughly 2" layer in my 50 gal. After seeing what happened when I washed it (no cloudiness of the first batch of water, just surface floaties) I poured the last bag in the tank straight from the bag. Sure enough, no cloudiness. There are 'bubbles' of sand that float on the surface if you don't wash it first, but these are easily removed. I haven't noticed a change, but I have heard that this brand of sand can cause pH to rise.