Orca Laboratories Nitra-Guard Bio-Cubes V4 - 500 mL The worlds fastest & most effective carbohydrate based nitrate remov More economical & effective than any other product of its kind in the worldnothing can compar Reduces 50ppm Nitrate to 0ppm within 1 to 2 weeks in Freshwater and Seawat Easy & convenient use, no daily feedings or dosings, just add as directed and enjoy 4 to 6 months Ni No more Deep Sand Bed Filters required which saves space, time and mon