HELP! I can't figure this out!

[doggie]

You say your levels are "perfect".

I'll bet most of the members here would like to know what those numbers are, before they try and figure out what it could be.

[Poconos]

The yellow stuff could very well be pollen at this time of year depending on where you live. Looks like a fine dust that is stirred up easily and will go right through a sand filter. Dug up this pic from last May when I had a really bad case of the stuff. Sucked some off the bottom of the pool near a seam where it settled, then looked at it under a microscope. Pretty obvious what it was. The lower right panel shows the calibrations for the other fields.
Al

Attachment 665

[matt4x4]

Howbout - check/read the very top sticky, could possibly be that if it's not pollen. Regular cl levels and even std shock levels don't affect this stuff.
Probably still too cold to get in your and check if it's got a slimy feel.