I use them also. When there is too much detrius flying around (waterchange, Aquascaping, cleaning back wall) I use them for a couple of hours.
I think I'm going to use them more often, because detrius collects in the sump, and I'm too lazy to clean it up every other day.
I don't use them at night, because the corals feed at that time. I clean them every time I used them.
btw, use the 200 Micron, not smaller. The particles that are food for corals (50-150 micron) can go through the bag that way
Leonardo