I have a 180gal FO tank that is running without a skimmer, currently
relying on a wet/dry and live rock. I want to add a skimmer to get the
water quality up and to help battle phosphates and algea.

I have looked at the ETSS Evo 500, AquaC EV-180 and Euro-Reef CS6-1.

For your size tank, I would suggest you look at the next model up of your
selections.

jc