Questions - Need some input

so I got a new skimmer last week and it was working ok But it was to deep in the water about 12 inches.
I got a stand built and know it sits at about 5.5 inches deep.

Manufature recomends 5-8 inches.

Could this be causing it to over flow?

I have it dialed all the way down both the air and the waterlevel. in the skimmer and its been over flowing for 24 hours st8 now

has anyone tryed these do they work I dont have space in my sump for biopelle reactor so If these work then its a great option for me.

Nitra-Guard Bio-Cubes from "orca labs"

hey so everytime i do a water change my skimmer goes crazy any ideas as to y it does this?

hey so i tryed out my new hanna calcium checker and got a reading of 600 which is the max on the checker?

any idea why this may happen?

How long can one keep pre mixed saltwater in a holding container befor using it for water changes?