nope, you are right on. it is closed and still overflowing. unless it is not perfectly on 0, but at most it is at 0.1. i usually have it set between 3 and 4.
what i mean by wide open is the standpipe should be letting as much water out the bottom of the standpipe as possible. the water level in the skimmer should be at its lowest. if you close the stand pipe the level rises and it will overflow, which is what you wouldn't want. turn it to max then
0, i guess is min has the lowest water level but the foam still overflows. when i turn it fully the opposite way the water overflows and there are minimal bubbles.
Have you used anything that is new? Like Frozen Food or any food Coral food or any type of Supplements. Did you happen to dose a little more of something or add little too much food a few days back. To me it just sounds like you have a major increase that is just making the skimmer react. I know if and when I feed Frozen food my skimmer after about 30 to 45 min. will just go nuts and slowly return to normal. Could be as simple as opening a new package of Frozen food and it just has a higher amount of organics. For now I would keep Skimmer at its lowest setting and add some Carbon if you have Carbon on it already change it and add some more to it, just give it some time it should balance itself out.