Hello, and welcome to the boards, Yes there have been alot of changes since the old days. A many new ways of doing things. As far as setting up your tank there are two main ways to do this. I take it your 75 is not a RR (reef ready- means not drilled in the back to drain the water from your tank) if not you are open to two options,
1). use canister or hang on the back filters. This option is ok.
2). Use an overflow on the back of the tank, This will bring the water down to another tank under the "display tank". This option is always best. It allows most of your equipment to be out of view, you can use bigger, better equipment that you would otherwise be able to use. and it adds water volume to the 75 gallons you already have. This is referred to as a sump.
A good idea would be to see what all this equipment is. Go to a LFS(Local Fish Store), inform them that you are researching what a sump is, and how it works, DO NOT, I repeat DO NOT let them talk you into buying any thing at that time. Unfortantly LFS have a very bad reputation of selling junk unnessary equipment to newbies. You just need to know what we mean when we say, sump, fuge, skimmer, over flows, etc.
As far as equipment goes. If you decide on the "sump" type of set up. You will need:
A smaller tank for the sump - one that fits nicely under your 75 in the stand.
Over flow kit - to get the water down to the sump
Protien Skimmer- This pulls waste out of the water. fish poo etc. A corallife Super Skimmer is good, ASM g-3 is better, euro-reef are also very good. Stay away from sea clone, skilters these are total junk.
Good powerheads - add needed circulation to the tank. At least 2 maybe 3. Maxi jets are good, Seio's better, Tunze best
Heaters- it is best is use two. If you need 300watt heaters, then use 2x 150watt. example.
A good RO/DI unit- this hooks up to your in house water souce, and will clean your tap water so it will be pure enough for saltwater aquarium use. This is $120 -300 bucks, depends how highend you want to go.
SAND- you will need about 125pounds of sand for a 75gallon tank, you can buy 100lbs of dry packaged sand and use 25lbs of live sand from your lfs to seed the rest of the sand for your tank, this will save you a lot of money.
LIVE ROCK- you will need at least 125lbs of live rock. You can use some base rock (not live) and seed it with the rest being live rock.
LIGHTING- you stated that you want a reef tank. So you might as well get the lights you are going to need right off the bat. For a reef set up it is best to use Metal Halide or T-5's, or a combination of both. Use the Metal for your daytime lights and the T-5s for your actinics.
There are some things I have left off. This alone will be alot to digest.
If you are good with your hands and have some carpentry, electrical, skills you can save your self a lot of money and build your light system yourself, same with your sump, there is a good DIY forum on this site. They can give you alot of the info you will need. But before you spend a dime, check out a lot of the different equipment that I have mentioned and see how it works, ask you local fish store about local reef clubs. Most major area have them. That is a good place to hook up with others in this hobby, they also can help figure out how to put together a sump set up and a killer light set up. It will also give you a chance to look at several different set ups. and see the equipment I have mentioned.
