The skimmer needs to break in first. All skimmers have a break in period of around 3-4 weeks. During this time, the skimmer will act erratically while the the water washes off the oils that came in the acrylic directly from the factory and a layer of bacteria grows and lines the inside walls of the skimmer. Once the skimmer is broken in, it will be very stable and almost hands off.
During the break in period, please try to keep the skimmer at the lowest setting and open the gate valve all the way. Tweak it as needed knowing that you will have to change it again every day or so until the skimmer settles.
Here is a good article on dialing skimmers:
http://www.coralvue.com/support/317511-How-do-you-dial-in-a-protein-skimmer
Regards,
Carlos
CoralVue