Setting up DCS170

I have been running my new DCS 170 on my 120gallon fish only tank for a couple of weeks. I have found that setting the pump speed one level below full power seems to work best. The problem I am having is that I can't get more than 7-8 hours before the skim cup gets full of foam and the foam goes through the holes in the top and the top lifts off the cup and starts running down the side. The skim that collects in the bottom (only about an 1/8 of an inch) seems the correct consistiancy as compared to other skimmers I have had and have seen.

I have experimented with different levels and a couple of different speed settings but the the foam still builds and lifts the top off. The current level is the water level slightly below the top of the cone and the initial foam top just going into the bottom of the neck. I have read the forum and looked at the FAQs but didn't find the helpful. I can send a picture as well if that would help.

I am also getting some bubbles out of the outflow, is there a way of eliminating those?

Thanks in advance for your assistance, George