Looking for a protein Skimmer with only 2.5 inches space between the wall the and the fish tank?

Question

I have a 72 gallons saltwater tank with 2.5 inches space between the wall and the tank. It also have 2 inches openning at the back of the tank. Any hang-on protein skimmer would fix the limited space. If not, any in-tank protein skimmer is good.

Answer 1

Do a search on any search engine for DIY protein skimmer. There are lots of plans online for making your own, so I'm sure you can find something you can make, or modify the plans of something you find to make it work.