Where do I begin....First of all, I would have had my tank pre-drilled for the overflow and had some form of closed loop system in place before I started. Decided to start a refug. ( a DIY project) and bought the mud, more LS and some macro algae from someone with an established tank, and a pump. The one thing I didn't buy was an overflow kit. That was my second mistake. As anyone can tell you from being there, trying to get the balancing act with gravity vs. the pump, it's a constant battle. You either have too much water in the display tank (hence the need for the overflow kit) or too much water in the refug. I would also suggest having a quarentine tank as soon as you purchase your main tank. That's my 3rd mistake....tangs and ick go together like PB&J. Much easier to put your new fish in a bareless tank (NO SAND OR ANYTHING ASETHETICALLY PLEASING)than it is to dismantle your LR and try to catch all your fish to treat them (cause MOST treatments will KILL the rock or invertabrates). If you can't afford a RO system in the beginning, go to where there is a Culligan water source. Mine here is 39 cents a gallon. Either that or sometimes your LFS will either give you some or make you pay a small fee for it (if they have a RO/DI system). LIGHTS, LIGHTS, LIGHTS...I don't have any corals yet because I still need to purchase some which require some good hard cash. Worth the investment. Remember to also not add all your fish at the same time. Spread it out a little. Your water numbers and protein skimmer will thank you. Otherwise bio load gets to much at one time. A good clean up crew is a MUST! I've always heard you need a hermit crab for every gallon of water in your tank. Snails, starfish (serpant, brittle or sand) are helpful since they love the detris that is in the sandbed and they also aerate the sand for you. Last but not least, ask a zillion questions and read/research the heck out of what fish, corals etc. that you want in your tank. When looking for what fish you want, make sure you know the adult size, compatability and how much you are willing to spend initially for those beautiful creatures. For the corals it's basically the same thing. Know where in the tank vs. the lighting system each coral needs to be, how they will get along with their neighbors, which corals need to be introduced first (cause some will wonder until they find their perfect home and then anchor) and what food they require. Some corals need to be spot fed with phytoplankton while others require real meat. I've only had my tank for 3 months, but I spent a lot of time reading and asking questions prior to setting up my tank. Sometimes though, you just don't know what questions to ask and that's where these message boards come in handy. Someone, somewhere has experienced it all and has talked about it. Good luck to all!