if your only changing it twice a week your going to be defeating the purpose
I'm using the 200 micron which is the 4"x8" one I believe. I have been changing mines daily but thats due to a weird slime issue I'm having still.
Same here, I find the water over flowing out of the sock everyother day. But I think 200 is the way to go, my 100 micron didnt last much after a few weeks of cleaning it.
Some people don't like to spend all their free time maintaining their tanks like you Matt.. I change mine 2 or 3 times a week and never have a problem...and I use 100 micron socks...