Thinking of setting up my first salt tank

[ron101]

First off, welcome to the hobby. Secondly, there is more than one way to run a reef tank so different opinions are often equally valid. One thing that is for sure is that starting off in the right direction in the first place does save time and money down the road.

I would seriously consider using a different tank. Not only does a 72Lx24Hx12W tank require a lot lighting relative to the volume but the short width will be a PITA for stacking rock and because of the higher density of saltwater, it will look about 9" wide from the front. So while that configuration gives max viewing for a FW planted tank it may not be so suitable for you for SW.

The T5 vs MH is an ongoing debate. Personally I have not seen any numbers that declare one decidedly superior to the other. MH run 'hotter' partially due to them being a 'point source' whereas with fluorescents the heat is distributed over several feet. I suggest you compare pricing AND appearance and see which you prefer.

FWIW I successfully kept softies, lps, lower-light sps, and bubble tip anemones in a 24" tall tank under 10000K 175W MH for years. If you want to go with 'bluer' 20000K lamps factor in that as color temp goes up, usable output and lamp life goes down.

As for the sand issue, if you like black sand use it. Sand will have limited buffering ability in seawater since the water already has a higher pH and carbonate hardness. Unless you run it in a calcium reactor setup, your carbonate and calcium replacement will have to come through additives such as kalkwasser, calcium chloride, and sodium carbonate/bicarbonate.

I have had a few pieces of tuffa in my system for years. It's all encrusted now and difficult to differentiate from reef rock. So I would day use some (as long as it is relatively pure) if you want to save some money. Since it is so soft you could even drill some rough channels through them to make passages.

HTH