what is this

[cheeseburger]

is it a protein skimmer or what is it? i am confused now
http://www.guppysaquariumproducts.com.au/canister-filters/new-surface-skimmer/prod_419.html

 

[dmopar74]

its a surface skimmer adapter, same principle as an overflow, it just sucks in surface water.

 

[proaquatics]

 

[BIGgourami]

yup all around