Sand.

Question
QUESTION: I found this white playsand that is already washed and is natural washed sand. Its very fine so it the turtle eats i guess he can poop it out without a problem. Can i use that sand or is it still a risk.

ANSWER: You didn't say what species your turtle is, but unless it's a softshell sand isn't a recommended substrate due to the impaction risk.  It's best to use something that is too large to swallow, such as river rocks/stones.  Another alternative is to leave the bottom of the tank bare, which isn't pretty to look at but does facilitate cleaning and is especially helpful if your filter isn't too powerful.  Hope this helped!

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QUESTION: I have a southern painted and a 40 gallon filter for my 20 gallon long. I heard that river rocks hide depris and can be really nasty to clean and when turtles dive of a basking platform it can damage there shell. I have a bare bottom currently but I want to give the tank a cool natural look to it.

ANSWER: The decorative river stones that are smaller (2" size or so) aren't too difficult to move around and clean, and with adequate water depth plastron damage shouldn't be an issue.  Sand can actually be pretty difficult to clean, and I just don't like it because I've known of a few cases of turtles ingesting way too much of it.

If your turtle is mature, the tank is too small.  You really need something more in the range of 50 gallons, with an adequately sized filter.  Bigger is always better with turtles, and a larger size will improve water quality and help to reduce the need for more frequent cleaning.  A poly stock tank, Waterland tub, or even a large Rubbermaid bin are other options, although not as aesthetic as a tank.

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QUESTION: He is only 2inchs or 2.5 right now. I possibly do have a plan for a larger tank. Go with the 55 gallon or the 40 galllon breeder?

Answer
You have some time for him to grow into a larger tank, then.  I'm not sure about the dimension differences between the 55 and the 40 breeder, but I'd calculate the area and see which is bigger.  You want maximum swimming area, so the overall capacity doesn't matter as much as the "floor" area does.  Here's a chart that has all the tank dimensions--it's old, but as far as I know dimensions haven't changed:  http://www.thekrib.com/TankHardware/size-chart.html.