My solution to a bare bottom tank...
When I finally decided on the tank I wanted for the family turtle, the recommendation by the pet store was a bare bottom, no stones. But I wanted the tank to look natural.
So here is what I decided to do to solve the issue:
Bought a 29 gal kit that has a filter, basking light, UV light, plant cluster and floating basking area.
Instead of putting stones on the bottom, I went to WalMART and bought two cans of multi-fleck spray paint in sand colors. I bought two different colors of general earthy tones and a can of frost paint.
I masked off the entire tank except the tank bottom and back (painting the out side of the tank ONLY) Holding one can of the fleck paint in each hand I sprayed some areas dark and some areas light to give it a natural blending on the bottom of the tank.
For the back I painted the fleck paint only to the height of the water level, this was done freehand so that there is not a straight line but a fading level, say about 4-5" high in the back. For the remaining area in the back I painted the frost (so that you can't see through the back of the tank to anything behind the tank).
I let it dry over night and set the tank up the next day. I must say, it turned out much better than I expected and really looks good. It looks like sand on the bottom. I added a couple large rocks because the turtle was having difficulty getting onto the basking stone.
With the smooth bottom the tank it is really easy to clean using a real fine net scoop.
So, for about $10 of paint, I didn't have to buy stones or a background picture and I don't have sediment building up in the stones on the bottom.