It works fine for me. I have a double chamber over flow. I did have a clump of algae partially block my drain as I was trimming once, but like I said, I have 1 drain and a long wide box the width of my tank, with a partition in the middle. It grows chaeto with the intensity of my halides...it grows faster than you would believe. Once the box is stuffed full, you don't have to worry about anything going anywhere...its when there is only a little bit that there is any danger, because it doesn't have enough mass to hold itself in.
I can send pics if you'd like.