Seachem Flourish Trace 250 ml (8.5 fl. oz..). Supplies a broad range of trace elements demonstrated to be necessary for proper plant growth. Trace elements are usually depleted by utilization, oxidation and precipitation, thus it is important to restore them on a regular basis. Flourish Trace may be used alone or in conjunction with Flourish. Flourish Trace is Nitrate-Phosphate free. A 250ml bottle will treat 200L (50 gallons) for 2 to 4 months