bacterial slime in sump

[Proteus]

This morning I pulled a water sample from sump to test mg. I noticed that I have some clear slime on water surface. I do belive it to be bacterial from the carbon dosing (zeo) and am wondering if it's bad for tank inhabitants.
When I get.off work I'm going to.clean out sump and flush.it with nsw to be sure it's gone.

Is this normal?

I've slowed my return down in the last week to allow more dwell time for skimmer to pull surfactants out. Doing so my skimmer has improved.
Also added three new fish in last week