Dr. Dai Phan
Aquarium Advice Freak
- Joined
- Jun 13, 2008
- Messages
- 231
They are micron socks used to catch debris, but must be changed often (washable): 16" 100 MICRON FELT FILTER BAG W/RING: Premium Aquatics
I prefer a reactor such as: http://www.marinedepot.com/ps_ViewItem~category~Two_Little_Fishies_Phosban_Reactor_150_Phosphate_Reactors~vendor~Two_Little_Fishies~idProduct~TL4311~idCategory~FIFRISPR.html
I do use filter socks though to catch the larger particulates.