could be that you just turned it on after a heavy feeding? My skimmer (Turbofloater) will oveflow if I turn it on right after a heavy feeding (when I feed fish anemones and spot feed the corals at the same time)
Past few days my bubbles have been overflowing the lid, haha. I think the skimmate was too dry/thick...so I opened up the 'valve' a little more. I had it close to closed, so not much water was gettin in.
I'd be intersted in your solution. I just got my RS80 2 weeks ago, just waiting for my sump to be built. For the RS80 it says the sump water level should be between 6-8" and that the return tube exit is above the water line, not below.
A high surface tension will cause a skimmer to act up and fill quickly as well. But it really sounds to me like you have the water level to high. As Eel-byte said it your water level for the skimmer should only be about 6-8" or just above the pump.
i have an rs80 and i have it submerged about 8in like recommended and it works wonderfully. i've never been happier with a skimmer, pristine water and no more algae on the sand! how long have you had it? they take some time break in and you have to play around with it like other have stated. i just turned mine on after being off a couple days and it's going crazy with bubbles too, but it should calm down soon.