Personally, I don't believe in any of those products. All they really do is chemically bind to the nitrates and inactivate them. Then the bound nitrates are still in your tank.
The best way to get rid of nitrates is through good biofiltration (live rock, live sand, macroalgae), skimming and most importantly, REGULAR WATER CHANGES. The later one most often being the most overlooked. With the biofiltration, the nitrates get broken down even furthur into harmless waste products (nitrogen) and exit your tank.
I have had my 125 reef up for several years and rarely even check the nitrates as they have been zero for as long as I can remember. A while back, I droped in a small peice (~3 pounds) of uncured LR into the sump (it was a really cool shape and looks great so I bought it) and my tank's parameters did not budge as the biofiltration could handle the hit from the rock. I do not recommend doing this, but it is an example of how a healthy system can filter out waste products.