One of my guests to our spa got into the spa after using an artificial tanning product. Now, about every three days, a scum line forms that is very sticky. Also, I have a sponge type floaty thing that absorbs some of this oil/scum, but I have to constantly clean it. Will the liquid bleach that I use for sanitizing eventually take this out, or do I need to shock and aerate to be rid of this stuff?