MicroBacterSTARTXLMProfessional 15x strength live tank starter nitrifying bioculture for rapidly cycling new marine fish and reef aquaria and brackish aquariums, and for recovering from overcrowding or disasters where the bacteria bed has been damaged or when adding new fish. Useful for rapidly re establishing nitrification bacteria in case of an emergency Particularly useful in aquaria with high population densities and when adding new fish Helpful to re establish