Removing shell/lime from sand

Is easy and cheap.  Buy muriatic acid (used for etching cement) at
your hardware store.  Put your sand in a 5 gallon plastic pail and
add water just over the sand.   Add a cup of muriatic acid and stir. 
Wait an hour and stir again.   When you stop getting bubbles when you
stir, add another cup of acid.  If you get no more bubbles, rinse 10
times carefully and use.  Otherwise, proceed as above (stir and

CAUTION:  Muriatic acid etches cement.  It is not for children or
folks who will not read and heed directions.   It is perfectly safe
if you are careful with it but it is like bleach or drain cleaner,
pay attention!  If you spill it on your skin and do not wash it off
right away it will blister you.  If you pour it in your eyes you will
probably go blind.   That kind of thing.   Use your head and follow
instructions.    Dave

Dave Gomberg, Experimenta      San Francisco CA USA   gomberg at wcf_com