Tech-M Magnesium supplement is a ionically balanced product which will safely raise the magnesium level in any marine system without upsetting the ionic balance of the system. Tech-M is very concentrated, containing over 70,000 ppm of cationic magnesium, and is nitrate, phosphate and gluconate free! Directions: Important: Shake vigorously immediately prior to use! The preferred method is to test the magnesium level in your aquarium, then add Tech-M at the rate of 1 ml per gallon aquarium capacity per day to bring the level to between 1250 and 1350 ppm. This will raise the level by 18.4 ppm per day. As a routine supplement, if not testing, add two teaspoons (2 capfuls or 10 ml) per 50 gallons tank capacity every week in all marine systems. Contents: deionized water containing the following elements (as ions): magnesium, chlorine, sulfur, calcium, potassium, bromine, strontium, boron, fluorine, lithium, rubidium, iodine, iron, molybdenum, zinc, nickel, copper, manganese, vanadium, cesium, cobalt, tungsten, selenium, and chromium.