TwoLittleFishies CombiSan (New updated Formula) is a bio-activator that contains all essential trace elements in special compounds easily absorbed by invertebrates, micro-organisms,marine fish. You can depend on CombiSan to replenish deficiencies in the composition of aquarium water resulting from protein skimming, use of activated carbon, biological processes, precipitation,extraction from the water by marine life. CombiSan fosters the development of pink calcareous algae, the rapid growth of reef building stony corals. It promotes tissue repair in fish, brilliant coloration in photosynthetic corals, anemones, Tridacna spp. clams. It`s the one marine supplement that does it all. CombiSan is nitrate, phosphate free! 250mL (8.4 fl. oz.) bottle. Dosage: 2-5 mL per week per 25 gallons (100L).