I'll look at the other, later, but a BIG WARNING right now:

If you've already used a "bunch" of clarifier, do NOT use any more, and do NOT use any floc.

Regarding the filter: if it was DEAD algae that was blowing through the filter, yes, you probably should open it. If you want to be sure, get some DE filter powder, put a couple of cups in the skimmer, and then see if that blows through. If so, your filter definitely needs service.

(PS: the "pump" photo is actually the pump MOTOR; you need a picture of the pump wet end, too.)