Film on top of water

Hi- I recently started dripping kalk through my ato system. I have noticed a thin film on top of the water in the sump, especially by the float valve where the water enters from the ato (Kent Float Valve) I decided to put a very small power head in the sump compartment to gain a little agitation. Is this ok?? I do mix the kalk and let it settle out before use. I also tip the 5 gallon bottle a bit to ensure no slurry.

 

We have a power head in our refug. also so that shouldn't be a problem. Better to keep it stirred up a bit but not too much. IMO

 

thanks

 

does it look like a oil slick on the top of the water might be protiens u can try to get it off the top with a paper towel just leave it open like a sheet