Little children and swimming pools will work out ok providing that the children are supervised at all times. You basically need to have one adult per kid to watch out for the child.
I'm gonna guess that they are mosquito larva, but I may be wrong. Are they little squirmy things? If so, proper cleaning and turning the filter on more often will prevent kill and prevent them.
If you mean calcium deposits at the water line, you can contact a professional who uses mineral salt instead of glass bead blasting. Here is a list of service professionals...