ReefRocker is right.
And this is in no way any commentary towards the Zeovit system, but just so Expedition will know....the basic 4 that Deuce refers to will run you about $100 + shipping for the first 6 weeks of useage. Then you'll need to change out the zeovit rocks on a regular basis, which is another $20 bucks or so. I'd guess for a 75 gallon tank, it'll run you about $25/month in total costs, and I think you need to be somewhat committed to it for the long haul.
Of course, you'll also need a reactor and a pump ($75 DIY or buy one for $200).
The other supplements that ReefRocker recommends have generated some favorable reviews, but they'll set you back another $100 for the smallest sized bottles.
Not meant to discourage, only to inform!