Sorry I missed your post earlier. Two thoughts for what they're worth:
I have seen that people who use robots no longer brush/vacuum the bottom of their pool and often get a dark line around their main drain as the robot can't really scrub there. Use a manual brush periodically to help with that. It takes many rounds of brushing as organic staining has occurred around the drain from leaves and other debris.
We have a very similar "gummy" substance. Ours didn't start until our pine trees grew and began to almost overhang the pool and we found more and more pine cones and needles in the pool. The pine cones themselves are loaded with sticky sap. I wipe out my skimmers with tons of paper towels on a frequent basis.
No parameters have changed in our pool except that the pine trees are growing so I attribute the "gummy" stuff in my skimmers to sap. It's sticky stuff. Btw, it loves the "back side" of my skimmer as well. It's looks like a grey waterfall on the back of the skimmer.
I have seen that people who use robots no longer brush/vacuum the bottom of their pool and often get a dark line around their main drain as the robot can't really scrub there. Use a manual brush periodically to help with that. It takes many rounds of brushing as organic staining has occurred around the drain from leaves and other debris.
We have a very similar "gummy" substance. Ours didn't start until our pine trees grew and began to almost overhang the pool and we found more and more pine cones and needles in the pool. The pine cones themselves are loaded with sticky sap. I wipe out my skimmers with tons of paper towels on a frequent basis.
No parameters have changed in our pool except that the pine trees are growing so I attribute the "gummy" stuff in my skimmers to sap. It's sticky stuff. Btw, it loves the "back side" of my skimmer as well. It's looks like a grey waterfall on the back of the skimmer.
