Hello R2R! I’m a HS teacher looking for a summer hobby, that on advice from a neighbor reefer, is going very slowly to set up my first marine tank. So, it’s about to become a Fall/year-round hobby! It’s a 75 gal SeaClear System II that I had as a freshwater tank for the past 6 years. As of today there’s 50lb of rock on crushed coral/black sand with half of the blue bioballs still in the sump area. No fish yet, just feeding the tank waiting to see my NH4 sticker thing show me some bacterial activity. Neighbor advised a protein skimmer, but am waiting to see if there’s one that’ll fit in the back of my unit…. can’t wait to add some fish soon. Thanks for any advice