Hello, I am new to this site and forum. I found it when I Googled the black grease in skimmer basket topic. I am trying to figure out what is causing it. It’s been over a week since anybody has used the pool and it’s still getting in there. However, the users did use sunscreen but we used sunscreen last year and didn’t have the grease. Plus my son has a pool 5 blocks away and they use sunscreen and he’s not getting the grease. We have a lanai so the pool is covered. We have had a lot of oak tree seedlings land on top of lanai and when it rains some of the grit from them get in the pool. The only other thing that I have changed is I started using Algae Control per Leslie’s Pool Co’s suggestion when I had my water tested a few weeks ago. So what is everybody’s thoughts on the cause of the black grease?