If you use this easy-to-remember ratio for the salted water, you can easily de-sand Manila clams (asari). This ratio works for surf clams (hamaguri) too.
Since there's only two of us, I always buy a small pack of manila clams. I thought up this ratio for removing the sand that only uses a small amount of water and is easy to remember. This is my memo.
If only using a small amount of clams, you can use a flat bottomed bowl to remove the sand. (The main photo shows the clams in a small colander rather than a tray.)
Enjoy Japanese food around the world.