Hey y'all. I'm a newbie to salt, and to this forum. We just set up a 20gal tall that our niece gave to us when she upgraded. We used live sand/rock and her old filter for the initial set-up. We also purchased a 240gph power head. We're now established with 10 hermit crabs, 5 cone snails, and 5 of the snails that snorkel through the sand. As for fish, we have two paired clowns. We had a spotted goby, but it developed some sort of sore on its mouth and died. Our water is staying mostly great with water changes and top-offs, but we need to find a protein skimmer. We're looking for a HOB that will perform properly in 20gal. There are several on Amazon, but mixed reviews only lead to more questions! We have the opportunity to purchase a CPR backpack, that a guy had on his 40gal. For $75 it seems like a great deal, but we just want what will work most perfectly for our tank. Basically, what's too much skimming, and what's too little? Sorry for the long winded post, but I wanted to describe what we have in the initial question since it seems that EVERYTHING is a factor. Haha. Thanks for any help. We're looking forward to many years of salt. We're already hooked!