Sump now going, but main tank cloudy?

[andsoitgoes]

As I was heading out for work this morning, I noticed that my water in the main tank was lightly cloudy (pretty much exactly what it looks like after adding the liquid reactor) - but the water in the sump was as clear as day...

I know I have no pictures or any test results, but everything is flowing properly, any quick thoughts on an easy answer for what might be happening, and what I can look for when I get home?

Thanks!