Sand pit sand has stained clothing, any recommendations?

[Anonemouse1]

i brought sand out sand from Argos for a new sand pit. Kids love it but staining all their clothes and after a soak/vanish/another wash I've realised I may not win against the stains.

Need two recommendations. Firstly, any clever ideas to get out the sand stains? Horrible brown colour. (Want to pass clothes on rather than be for one child)
Secondly, any recommendations for sand to buy as think I need to replace what I have.

Thanks All.

Should read sand pit sand on first line, can't edit the original post