I just finished using it on my 280g reef. Nitrates were 60ppm before I used it, and 2 when I weaned my tank off of it.
Nitrates continued to come down during the 60 day period, and PO4 was 0 the entire time. I did get a film algae on the glass that was super easy to remove, and didn't see green or brown film algae. This was almost whitish.
The only negative I had to deal with was cyano. Man-o-man. It got so bad on my sandbed that I had to resort to siphoning it out of my tank twice.
Still, all my livestock that I've had for years did very well, and that includes SPS, LPS, BTAs, Zoanthids, Leathers, mushrooms, my clam and all my fish. I have no problem recommending the use of this product, but I did use it more slowly than recommended to avoid shocking my livestock that had been in elevated NO3 for so long.