Liquid Fulvic Acid Concentrate with Magnesium. Fulmag is a multi-purpose liquid derived from the mineral leonardite combined with magnesium. It is a growth stimulator that increases the number and quality of flowers and fruit set, and it helps with the plants ability to uptake other nutrients. 1 gallon concentrate makes 256 to 426 gallons of solution. Dimensions;. Length: 6.75. Height; 10.25. Width: 4.25