Yesterday my hubby and I successfully installed a new Hayward 19" Sand Filter We used the sand shield that came with it while we added the sand. During backwashing, I noticed a little sand coming into the sight glass. I fear that sand got into the center even though we used the shield. I cannot see the bottom of the pool due to it turning green (old sand filter cracked and we couldn't replace it right away) to determine how much if any is coming back into the pool. Is this issue something I should worry about? If so, what can I do about it? Thanks for any help!!