Another link DIY swimingpond
http://www.grit.com/Tools/Build-Your-Own-Natural-Swimming-Hole.aspxI also think the chemical aproach is no good.
Part off the pond zones have to be reservated for the natural cleaning job off the water.
The quality on the water will deepend on the flowpatern you can create within the pond it self, or if posible a flowthru system.
Don,t expect a bluelagoon, then you can get disapointed, but fore sure you can make a fantastic swiming pond.
A thumb rule here is aprox 1/3 of the pond area is the swiming zone the rest of the pond is the filter zone, when you dig it remember the need for shalow areas for filter plants.
Good luck, it will be exiting to see how your project dewelops, and remember kids tend to love the aquatic life as a playground even more than the swiming part.
