Protein skimmer.

[phillrodrigo]

I have a mag 9.5 on my 75. It also connects a 20 h.

 

[Bob46]

I got a Reef Octo BH-90 love it. Started skimming 10 minutes after I put it on my tank and its super Quiet.

 

[izzyish]

I purchase a Vertex Omega 150 and it works awesome in my 120. Pretty quiet and sleek, I would recommend it to anyone.