oh, boy.....no answers for this one, huh? maybe if I throw something out there that's WRONG, someone SMART will correct it for ya.
Okay....I guess I'd try a couple different things.....
1) pick up one of those little floating faces/flowers/balls, scum balls, whatever....they absorb surface impurities, oils, etc.
2) clean your filter(s)....if you've been spraying them with a hose, try a chemical filter cleaner designed to remove oils, etc...then run your tub's jets for awhile to let the filters collect the 'stuff'.
3) try adding a little clarifier and running jets.
I'm sure I'm off base by at least a little, but hopefully someone good will chime in soon.
Good luck!