Quote Originally Posted by PoolDoc View Post
Actually, with a sand filter, if you'll remove any chemicals or tabs from your skimmer, you can LOWER your CH by adding the cal hypo via the skimmer. You must be 100% certain that there are no OTHER chemicals the cal hypo will contact, before you do this! And do it cautiously -- small doses -- at first, to make sure the calcium doesn't blow through your filter.
Other chemicals such as what? How would I tell?