Yet another tank build from a new member. I found a 72 gallon pre-drilled bowfront aquarium with a stand and plumbing on craigslist for a great price. It's a pretty big tank (4 feet wide)! I rented a U-Haul cargo van and picked it up last weekend. The tank was previously used for freshwater fish, and I verified that the person that I bought it from was the original owner, and that he had never used any copper treatment in the tank. First things first: get the tank masked up and ready for painting the back surface. Plastic dropcloth, painters tape, and Rustoleum flat black spray paint. I sprayed about 4 thin coats, then let it dry overnight before touching the painted surface. I mounted a power-strip inside the cabinet and placed it in the room where it will stay. The power-strip has a low-profile plug since the tank sits in front of the outlet, and I also strung an extension cord (also with a low-profile plug) behind the tank, which will eventually supply power to a chiller. You can see it peeking out from behind the cabinet in the third photo. The sump is an Eshopps refugium, model R-200 (30x14x16" LxWxH). This is essentially the largest sump that will fit into the cabinet. I could have gotten a smaller one, but I want the skimmer compartment (on the left side of the sump in the photo) to be large enough for my intended skimmer. In fact, the footprint of the sump is so big that I had to lay a couple of 2x6 boards on the floor of the cabinet to lift the sump over the little door-catches at the bottom front of the cabinet. I like that this cabinet doesn't have a center-post, which makes it easier to insert/remove/access the sump. Other equipment worth noting: * The return pump that came with the tank is a Via Aqua VA2600 (740 GPH). I think this should be enough water turnover. * The refugium light is a nice little clip-on WavePoint 6", 8-watt LED light. * The skimmer that I plan on getting is a Reef Octopus POV-DC1, rated for up to 200 gallons. * The chiller that I plan on getting is a Teco TR15 (0.2 HP). * The substrate is CaribSea Aragamax Select 0.5-1.0 mm diameter (3x 30 lb bags). I am paranoid about copper, so I rinsed the aragonite with filtered water only (I have a RO/DI system). Because of this, and because I'm anxious to filter enough water to fill up the tank, I didn't do as thorough a job rinsing the aragonite as I should have - so the tank becomes very cloudy every time I pour in a new 5 gallon jug of water. My plan is to fill up the tank completely with filtered water (without adding salt mixture), then run the water through the sump/filter system for a few days. I'll line the "sock" at the entrance to the sump with some cheap felt, and I'll stir up the sand many times to kick up as much fine silt as possible, with the intention that it runs out the overflow and gets caught by the felt (which I'll then toss out). I want to make sure that by the time the tank is inhabited, it doesn't get too cloudy every time the substrate is disturbed. After the in-tank aragonite rinse is done I'll add the salt, then a handful of dry rocks, then start the cycling process with live rock. I'll essentially use the following recipes for "maturing" the tank, with modifications for an octopus tank (not introducing fish, etc.): http://www.reefsanctuary.com/forums...arting-your-first-fo-fowlr-marine-system.html http://www.reefsanctuary.com/forums/fish-diseases-treatments/29836-mature-aquarium.html I like those two descriptions of tank preparation because they are very thorough, and also make it clear that "cycling" the tank is only the first of two major steps, and that the tank needs to be "matured" after cycling.