white sheen on top of pool water. What is it and how do i remove

[brusknj]

Hi I have a vinyl in ground 17500 gal pool that I opened several weeks ago. ph is 7.2 chlor 4.0 free is 4.0 all other levels are within normal range. Today I noticed a milky white sheen on the top of my pool water. So far filtering for the past 12 hours does not seem to remove. I tried using skimmer net also without success. Any ideas what is it and what can I do to remove.

thanks
Bill