I went with a 72" fixture for my 125g reef, but I wanted a 12 bulb system abd it was priced right on craigslist.
I wanna have mostly corals in mine so thus the need for alot of light.
If you build a canopy then you would get different light that can mount to the wood top and stay hidden. here is a picture of how my tank is with the lights.
I use the siphon or my python siphon to remove the water, same as my FW
tanks. BUT you need to add the new salt water back in via buckets or a pump in a garbage can for instance.
I make my ro
water and it goes into a 32g garbage can. I add the salt and keep a powerhead in there to mix it up. I usually do this the day before a water change. I bought a small submersible pump and some hosing from home depot and have the water pump from the garbage can to the tank instead of doing buckets.
I don't worry about temp matching as much since I live in Florida.
Just make sure the salinity of the new water matches the current tank water and youre pretty much set.