Reef Trace, 2 L / 67.6 fl. oz. Concentrated trace element supplement for reef aquaria Supplies a broad range of trace elements that are normally depleted rapidly by utilization, oxidation, and precipitation Replenishment of a number of trace elements is required to maintain an environment ideal for growth and reproduction of marine life May be used alone or in conjunction with Reef Plus; best results are obtained when both are used 250 milliliters treats 1000 US gallons