Ok, I think I'm going to take the plunge and upgrade to a bigger tank. My 90 gallon is just too small for my every growing collection of LPS and SPS. I have an opportunity to buy a 180 with new bulheads and a closed loop. The owner is upgrading himself to a 360 and I know he takes very good care of his equipment. I've never really paid attention to a closed loop system nor do I think I've seen very many in person so I have some very elementary questions here for you that are wiser than myself. The closed loop eliminates the need for in tank powerheads, correct? How do you figure out what size pump you need for your system? (I will be 180gallon with 75 gallon sump.) What brands do most of you think are the best bang for the buck? Would the closed loop pump be able to live under the cabinent and how much is the closed loop going to effect the distance the tank will have to be from the wall it will be against? Any factors that I have not considered here other than I'm going to need another job to get this system complete? If I add more rock (and I'm sure I'll need to although I have quite a lot of LR currently) I'd like to go with Marco Rock or something similar. I know it takes a while to cycle. How complicated is that going to be other than a big container and PH's? I sure don't want to buy a skimmer to cycle rock, what suggestions or would it be possible to rent one from someone?? lol Thanks for all your input in advance. I'm sure I'll have more questions. Other than affording an upgrade, I have to focus on how I'm going to break this idea to my husband. I think I'm going to start with his favorite meal and a double batch of choc chip cookies. Wish me luck!