You might take a look at this article. It gives some other possibilities and some explanations about why a haze may still occur in a well established, well filtered tank. It's a good read, but I'd be very careful with implementing the hydrogen peroxide solution.
Take note of the final paragraph.
Cloudiness caused by phosphate buffers. When phosphate buffers, such as Aquarium Pharmaceuticals' Proper pH, are used in hard water that has Ca and Mg levels well over 100 ppm, the phosphate can precipitate calcium and magnesium and adsorb them to itself, causing a haze. You should read A.P.'s Product TechSheet for their stabilizing pH phosphate buffers before you use these products.
I know my Ca and Mg is high, and I have the same slight haze when looking through the tank side to side. Doesn't bug me enough to reduce the levels or attempt risky solutions.
HTH
Take note of the final paragraph.
Cloudiness caused by phosphate buffers. When phosphate buffers, such as Aquarium Pharmaceuticals' Proper pH, are used in hard water that has Ca and Mg levels well over 100 ppm, the phosphate can precipitate calcium and magnesium and adsorb them to itself, causing a haze. You should read A.P.'s Product TechSheet for their stabilizing pH phosphate buffers before you use these products.
I know my Ca and Mg is high, and I have the same slight haze when looking through the tank side to side. Doesn't bug me enough to reduce the levels or attempt risky solutions.
HTH