HRTFILTERS 5 Pack Nylon Mesh Filter Socks 4 Inch Ring 50 Micron - by 15 Inch Long – Aquarium Water Filter Bags (50 Micron)

All Good except these filter socks make my skimmer go nuts for a few days. After they have acclimatised to reef tank salt water they are fine, but best to soak in salt water for a week before introducing to your tank, or turn down your skimmer to minimum for a few days. Cannot comment on fresh water usage

First time use sent my Skimmer crazy, must be some oils or similar contamination. Ok if rinsed out and dried first. OK on subsequent use