I would go with the largest your wallet can handle. If you are thinking corals now, I would go ahead and plan on a reef tank. It's cheaper to do it right the first time rather than change things up down the road.
Judging by the area, You have room for a 6ft tank. A 125G is 6ft, and would fit comfortably in that spot giving you a little space left over. Do you want acrylic or glass?
125G flow estimate: 1250gph for good filtration. (4 Maxijet 1200's would work).
Skimmer - Possibly a Reef Devil for that size.
Lighting - If reef, I would do MH
, but some people prefer pc
because of heating.
Substrate - No CC
. Use sand. It will save you headaches.
Salt - Still in debate. Latest poll shows Kent and Oceanic.
- Only one place - liverocks.com 8)
With a tank that size, you will fare better with a sump. So, if you are in the market for a large tank, see if you can get it pre-drilled before you take it home. You will thank me for this later.
Maintenance - Water changes once a month. I do 15%, some do 25%. It really depends on your bio load.
I know there is more information, but these tips should help you along. HTH