Oily Scum In Your Hot Tub Pool&HotTub Oily Scum In Your Hot Tub Oily Scum Scum in Hot Tub Hot Tub Maintenance An oily residue floating on the surface or around the rim of your spa is not only unsightly, it’s also a wonderful environment for microorganisms to thrive and contaminate your water. There are several reasons you may be encountering this grimy...