Black oily film

[reidsmith]

Why is there a black oily film on my scum ball in skimmer?

[TSH Tech]

It's ok, your scum ball is doing what it's supposed to do. It's telling you a new scum ball should be added to the skimmer.

[Guest]

I have done that. My question is what my be causing it?

[TSH Tech]

Could be a host of reasons;

- Suntan oils
- Hair spray products, gels, etc.
- Tree sap, leaf oils
- Pump seal is leaching petroleum
- Overnight spraying of pesticides
- Smoke/ash from somewhere has settled into the pool
- wild animal taking a dip into the pool
etc...
pools just don't develop a oily dark film out of nowhere, something is depositing into the pool. Very difficult to diagnose over the internet.