Sand all the way! I started with a 10 gallon tank with gravel. When I upgraded to a 30 gallon, I figured I'd try sand. I LOVE IT! It looks really natural and my corys love it. I just switched the 10 gallon to sand yesterday. Best choice ever.
You will get a lot of different ideas about which kind of sand you use, and depending on what look you want and how willing you are to rinse it will change your decision. Ultimately, people have success with basically any sand out there. Here are a few options you have:
Aquarium sand: Comes in a lot of colors. Has little residue, so you don’t have to rinse it AS MUCH. It does still need to be rinsed. Most expensive.
Pool filter sand: Gives a white sand beach look. Grains are uniform size and slightly bigger. People say it is kicked up less. Between $8-$15 for 50lb bag. Tends to have less dust, so again do not have to rinse as much. May be difficult to find depending on where you live. I live in South Dakota, and NO ONE has this right now. Not even the pool and spa store. :S
Quikrete Medium grade sand: Natural tan sand color. Grains are a uniform size. (Make sure you get medium grade if you go this route. Fine grain is too fine and you'll have a mess. Large grain is basically like a fine gravel.) Found at most home improvement stores. Around $5 for 50lb bag. May have more dust then others, so you will need to rinse it a little more.
Quikrete Premium Play sand: This is what I use. Grains are slightly varying sizes as they would be in the wild. Very natural looking. Found at most home improvement stores. $2.67 for 50lb bag. Most dust of the sands, so it takes the longest to rinse, but is also the cheapest.
Warning: Not all play sand is created equal! Some people say absolutely not on play sand because it turned to mud, they had cloudy water, etc. If you want to go for a different brand of play sand or any other sand, make sure the package says its washed, screened, and dried. This will minimize the amount of dust.
If you are looking for black sand, Tahitian moon sand and black sand blasting sand are good options.
Regardless of what you choose, make sure you rinse it until the water runs CLEAR. I think most people who have issues get impatient any don't rinse it all the way. The better you rinse it, the better it will work for you. If it isn't rinsed well, you'll end up with cloudy water, and those little grains will kick up whenever you move stuff around, or vacuum.
Good Luck.
