I have the same skimmer and it works the same way for me, except not qute as much overflow as your getting. I can't remember the last time I actually saw it producing foam, but it pulls about 1 gallon a week out. It only does it when I'm not looking.

I set mine up the same way, if it overflows it just runs out back into the sump. I have a gallon milk jug on the end of the overflow tube.