rip_em,
dont worry about the jerks that replied. they were born that way.
somepeople are genetically handicapped by immaturity.
I think that one corner overflow should be fine. You are going to have a few powerheads in the tank for flow reasons and you want to minimize the amount of 'equiptment/crap' in your dislpay tank. Just make sure that your flow is pointing in ways that will deliver the detritus/left over food to your overflow. Definetly go with the external filter. have your overflow drain into a sump or wet/dry and add a skimmer like newtankman said. You can always pull out the bio-media(balls) and add live rock if the nitrates get out of control. you can even use one of the compartments to make a minifuge which helps tank stability in many ways.
Also, something you should consider into this eqaution is your lighting. Try your best not to skimp on the lighting.. you will end up needing to upgrade in the future. If you want a reef you should try and go for t5 or metal halides. It will be expensive, but will pay off in the long run. The better the lights, the more you can throw in your tank (diversity of corals, not necessarily quantity) and the better they will grow. People have had great sucess with PCs but most end up adding more intense lighting.
Make sure to try and start your tank off with liverock/sand if possible. It will mature your tank faster and keep the cycle short.
DONT add DAMNsels (bad bad fish!) to your tank if your local fish store reccommends it. they are used to cycle your tank by adding waste etc and are commonly used. The problem is you will need to catch them later and youll probably end up dissasembling your tank to do so!
Throw a peice of coctail shrimp in there and let it rot. Easy to cycle and easy to catch!
start off SLOW. I knew someone who added like 14 critters to his tank on day 6 of it running. I think he spent his entire tax return on 'disposable' fish because he kept killing them and replacing them. Each fish adds additional bioload to the tank and changes the chemistry.
Get a GOOD test kit, then check your results by bringing a water sample to your LFS. dont rely solely on one form of testing. LFS are notorious for screwing up!
AND... only add RO/DI (purified water to your tank) one of the biggest mistakes is to add tap water (although, again, some people have dont this for YEARS and have VERY nice tanks!) adding tap water is like adding toxins and trates right to your tank! and we work so hard to get those out!
Keep up on water changes (salt water) changes will keep water 'clean' and replace essential elements which means less additives (chemicals) for you to dump in.
OK LAST PART! read ALOT. research ALL your critters before buying them. Even little crabs can be a big problem if you mix them with the wrong thing. some people have gotten some MONSTER emerald crabs! and post and ask questions as much as you want!!
no one here is the ultimate expert and the information we have is always changing. Even the reefers who have been doing this for years are coming up with better strategies for thier tanks.
This is all I can come up with without writing a REAL novel. get some books and learn the basic guidelines like the 'for dummies' books to just get the basics. you will be fine! welcome to the addiction!!!!
