I love my Curve 9 also. I got the neck cleaner with it and I am glad I did. These things are beasts and love to remove sludge. That is a good picture of the sludge but I have my input from tank about 3" from skimmer intake and the the sludge is just amazing. I have and do own quite a verity of skimmers have come full circle and am running the Curve 9. The amount of air and bubbles that are created in the body is just amazing, it's Snow white in the body when you look at it, but the best part is that there is very little turbulence in the body so you get this very nice counter current happening like in the Old Days of Air driven skimmers and if you want to see how skimmer is suppose to work, see if you can find a Video on one or better yet pick one up and play with it it will give some good incite as to what should be happening in the skimmer body. Anyhow I believe the BM line of skimmers one of the most under rated skimmers and are probably the BEST BANG for the buck skimmers.
Curve 9 is my primary and Reef Octopus regal 170 is my back up.