LSM media from Caribsea. 1 gallon. Here is a pure granular elemental sulfur, with sulfur reducing bacteria right on it. This product can be used in a number of ways, and accomplishes the same job of nitrate reduction as our NO-NO3?. This product is ideal for dual chamber reactors, using our A.R.M.? in one reactor and placing the L.S.M.? in another. This results in a system that delivers elevated calcium, and reduced nitrates.