Without magnesium, you would not be able to hold the proper amounts of calcium and alkalinity, and they would simply fall out of solution. Magnesium is essentially a buffer between calcium and alkalinity and is slowly consumed by corals, algae, and invertebrates, and in most reef tanks magnesium will need to be supplemented over time.
Instructions: (8.4 grams of Triton Magnesium Increaser will increase 25 gallons by 10ppm)
Test your aquariums magnesium level, and determine the amount of Magnesium Increaser needed to dose to your aquarium, and dissolve the dry powder in RODI water. Once fully dissolved, slowly pour the solution into a high flow area of the sump or display tank. Wait a few hours and test the magnesium level of your tank.
Use these other additives for a super pure 2-part system: