What you are dealing with is the lack of a surface skimmer on the intake. This causes oils to build up on the surface and is only an issue when using hang on skimmers. You have a good quality skimmer, and deltec has a great reputation. I suggest calling the manufacturer directly and explaining your issue. They may have a modification already in the works, or may have another suggestion. Deltec is a great company and will be happy to have a conversation with you.
If that doesn't work, then try using one of the modifications from another brand, such as CPR or Remora. Here is an example AquaC Surface Prefilter Box
You could also use a "surface skimmer". These are available here JEBO Aquarium - Water Surface Skimmer Plus
. I have never used one and they appear to be very low quality pieces of junk that would break easily and frequently clog. However, the cost is low and it is worth a shot. If it performs properly it will dramatically improve your skimmer. If you do this, please let us know how it performs.
As for the particulates in the water, this is almost a necessary evil in a marine tank. It will settle down as the tank matures, but is something you almost have to live with. The only other option is to use a particulate / mechanical filter and rinse the pad every day. I do not like this option because phosphates tend to accumulate when using these filters, and then heavy algae growth occurs. The lesser of 2 evils is to notice free floating particles in the water. Adding a clean up crew will also help with this.