Hard to tell SoTex. No doubt today was extremely windy. That stuff could've blow-in from miles around. If it just happened today, I'd chalk it up to Mother Nature and this crazy wind. Hopefully you have a skimmer sock installed to catch it if you are fortunate enough that the wind is blowing towards the skimmer. Now if this stuff was there before the wind, certainly post a full set of test results and we'll see if anything looks odd. Have a nice evening.