With the new smart series, which I have, the listed skimmer chamber dimensions are equally misleading. They listed dimensions pretends that the filter socks do not exist, lol. I MAJORLY dislike the "C" sock holders, 1st because they are incompatible with any filter cup in the market. 2nd, even to replace a sock, you have to pull out their short section of blue tubing inside the sock (getting crud everywhere, probably), remove the sock sideways through the holder, put the tube in the new sock, put the sock in sideways, replace the tube. A pain in the butt.
Your return goes directly into the socks rather than in a small chamber before and calmly overflow into the socks- so expect lots of noise and splashing.
I also had to modify my pump, the return section is unbelievably undersized for the sump size. It all points to their desire to have larger advertised chambers instead of a real quality experience.
The spongey filter section before the return pump is larger than the return pump chamber itself.... ugh. The space for the return pump could have easily come from there.
Overall, I do regret my purchase. I could have gotten something much more convenient and useful at the same cost. I fell for the "OOOooo its pretty and new"- my fault, but I can resent the manufacturers choices.
In time I see myself making some heavy modifications to the sump.