Black Residue on Pool Cover

[KSpoolguy]

I have an undertrack automatic pool cover. Along the sides near the track (on both sides) and more pronounced near the cover box, there is a black residue. Is that normal? I am considering having a pool company come out and take a look but wanted to check here first.

FYI: This cover was installed late last summer. When I opened the pool up a month or so ago, I deep cleaned the cover, pressure washed the tracking, and sprayed down the pulleys.

 

[JasonLion]

This could be the result of suntan lotion/oil floating on the surface of the water. Oils, such as from suntan lotion, tend to get black and "gunky" before they break down completely. Using a scum bug (foam sponge thing that floats in the skimmer) and/or an enzyme treatment can cut down on oil related issues dramatically.

 

[KSpoolguy]

That was my initial thought. I do have a floating sponge in the skimmer and it probably needs washed or replaced (pretty gunky). I guess I was confused because it was on the top of the cover and only on the extreme sides.

 

[KSpoolguy]

JasonLion, one more question if you don't mind.

I have three returns (2 regular returns and one for the pool cleaner). The two regular returns have different flow coming out. The one closest to the pool equipment comes out pretty fast and shoots up through the surface of the water a bit. The second return is about what I'd consider normal. For the life of me, I can't remember if the flow is the same or more than last year (just put in the pool last year). Does that sound normal?

Thanks in advance!!