Never knew how good these work but if you suffer from film or junk floating around on the top of your water all you need is a powerhead (I used maxi jet 900) a water bottle and filter floss just cut the bottom if the bottle off cut 1 in notches a couple centimeters wide slide the bottle onto input of powerhead add filter floss (I also added some lava rock) then put it in your aquarium submerge up to about half way up the notches and plug in works great
