EJENSEN - Greetings
Nice avatar - Go Gordon!
The gate valve controls the level of the water in the skimmer and, consequently, the type of foam produced (watery vs. dry). No water should appear in the column, only foam, so when first turned on, the valve should be wide open. You then slowly close it until there is foam in the column and make adjustments from there. The directions recommend that you make changes to the valve opening in small increments and then wait to see the results. That is accurate - you should make changes in 1/8 turn (or smaller) increments and then wait an hour or two to see the results. It's surprising how much difference 1/8 of a turn can make, so take your time. What you want to avoid is creating foam that is too watery, which occurs when the valve is closed too far, because this can quickly fill and overflow the collection cup.
The web site for ETSS has a "Quick Start" guide that might help you. Got to
www.superskimmer.com, click on the "Tech Support" link and then the link titled ""Reef Devil Operation Manual". It is a PDF file that you can download and refer to.
Here are some additional pictures - thought they might help...