I couldn't agree more with Kurt!
I have a 125 reef, do 20 - 25 gallon PWC's every other week, but I'm now doing them every week.
I also have NP Bio-Pellets (solid form of vodka dosing) in a gfo reactor which keeps my nitrates under 5, and a dual chamber GAC/GFO reactor to polish the water and keep phosphates in check. I STILL DO PWC's at least twice a month.
Yes, there are those tanks that go months with no PWC's. They have 3 small fish in a 125g that is predominately SPS corals. They feed very lightly, overskim, and run carbon, etc.
More inmportanly they have years of experience and these started out as test systems that usually went through a crash or two before they hit the right combination for stability.
If you want to be in and out of the hobby in a year or less then try every shortcut in the book. If you want a tank that matures over time and gives you hours of pleasure (both the watching and the maintenance) then take the go slow approach and do it by the book.
These are my rules for a succesful SW tank:
Rule # 1. Nothing Good ever happens Fast in a salt water aquarium
Rule # 2. Don't add anything (supplements/chemicals/minerals)you don't test for first.
Rule # 3. PWC (Partial Water Changes) are your friend, and cure many ills.
Rule # 4. QT EVERYTHING before adding it to your tank (mandarins excepted, corals should be dipped)
Rule # 5. Use only RO or RODI water (either buy it or make it)
Rule # 6. All animal species live longer on a 30% reduced caloric intake. Only feed every other day at most (fish species dependant)
Rule # 7. Hyposalinity is the best, safest, and most effective treatment for marine Ich (IMHO)
Rule # 8. A Refractometer is a MUST HAVE, not a luxury.
Rule # 9. Anemones will never live anywhere near their normal (aprox 30 years) lifespan in a home aquarium. Leave them in the ocean.
Rule # 10. The tank size recommendations for fish are there for a reason - HEED THEM!