A PS while not required is a very good choice. Assuming the 75 is not pre-drilled you will need to get or make an overflow to feed the ps. This is assuming you will have a sump a/o fuge below the tank
Your lighting will probably be fine for
FOwLR. What is your current light setup? You will probably have to replace it when you want to add corals.
You will need test kits for ph, Ammonia (
NH3), Nitrite (
NO2) and Nitrate (
NO3) and possibly
PO4. Others such as
Ca and
Mg when you want to corals. I would suggest a refractometer for Specific Gravity (
SG).
A
RODI unit for filling the tank and make up water is a great investment.
Reading the
Articles and asking lots of questions before you make a final decision or buy anything.
A QT setup so you don't add any nasties to your new tank after it cycles.
Let me think back on the other mistakes I made and I might have more for you.
BTW, after more than 10 years in
FW I started
SW with a 125 gallon and I'm very glad I did. But, the bigger the tank the more everything costs...