snails

[vazgor]

ok guys i dont know if anyone can help me here but hear goes.
After my lights go out my tank is over run by little snails, up to about an inch long.The baby one's have red with white spotted shells and as they get bigger the shell becomes sorta irradesent.Are these bad couse i shure seam to be getting alot of them,and now i have also noticed some that have black and white checkerd shells.
now if these are bad how the hell do i get rid of them with out killing the good snails i paid for