Never but never use any additive/substance to deal with an issue unless it is safe and effective. A fish is continually "drinking" by taking in water via osmosis. Substances dissolved in the water that are able to diffuse across the cell membranes will enter into the fish's bloodstream and internal organs. These are always stressful, frequently dangerous. This applies to medications too.
Water clarifiers work by binding microscopic particulate matter into larger bits that can then be removed by the fine media (foam, wool, etc) in the filter, or the sponge filter. All very well, except the binding occurs in the fishes' gills too. Not good. So, do not use them.
As for Purigen, I have never used it but I think it may have a use, but someone familiar with it will have to advise us.
@AbbeysDad I believe used this in his nitrate fight, I will alert him to this thread.
To the cloudiness/haziness...this can have a few sources. Microscopic particulate sediment in the tap water (this can change with seasons and weather), not everything gets filtered out. Dust from the substrate (especially in new setups), which is similar to the aforementioned. It will settle out/filter out in time, leave it. Third and probably most common, a bloom which can be bacterial, organic or diatom. Organics feed these, and these organics can come in the tap water as well as the tank. The bacteria that feed on organics multiply very rapidly, and cause the cloudiness. Depending where the bloom comes from, it is usually best to wait it out, as fresh tap water in a water change can add even more. Normal water changes should continue, but not excessive.