I have tried IO, Reef Crystals and DD and Red Sea Pro in the past and feel the Red Sea Pro showed the best results in my corals after doing a wc. I would like to try Tunze or Reefer Best though.
Ocean Pure for close to 4 years now. Magnesium never a problem. Before that I used Tropic Marin and I always had to add magnesium. But back then there was no Pro TM.