Brightwell Aquatics MicroBacter Purple M is a concentrated blend of live purple non-sulfur bacteria (PNSB) for marine and reef aquariums. These beneficial microbes help drive down nitrate and phosphate, improve water clarity, and encourage rich purple and pink coralline color, while also serving as a supplemental food source for corals and other filter feeders.How to UseFollow the label dosing for your system volume, starting conservatively and increasing gradually. It can be dosed in light or darkness and works well as part of a regular reef maintenance routine.Specifications Type Live purple non-sulfur bacteria (PNSB) Benefits Coralline color, nutrient (nitrate/phosphate) control, coral nutrition Water Type Saltwater and reef Sizes 125 mL, 250 mL, 500 mL, 1 L, 2 L, 4 L Made In USA Pairs Well WithPart of a complete reef dosing routine with your corals and other additives and supplements.