NPS = nonphotosynthetic correct?

I would run the filter sock if it makes you comfortable. Maybe even try it for a while w/out to see how bad it is. I just had a lot of "foam" ups from my sock and that is why I run w/out for now, but I do have a lot of maintenance that has to be done in the sump/fuge when I don't run it. I am waiting for my new ones to get here and then I will return to running w/ them - they are just a bigger mesh size than my old ones.