I think this is an apples to oranges comparison. This is just my opinion but DD has high alk and is more comparable to RSCP whereas Brightwell has lower alk and is more in line with Tropic Marin. So depends what you want out of your salt. If you run nutrient rich then I'd say give DD a try. If you have 0 nitrates and undetectable phosphates, and dose or run a CA reactor then Brightwell might be a better option. just my .02 cents