I run a fluidized bed sand filter instead of bio balls in my freshwater set up, keeps my nitrates down and ammonia down as well. Sand covers 10 times or higher the surface area of bio balls. My bed runs under my system clear pvc filled with sand, water enters from the bottom and exits the top into my sump slowly, and works amazing. My question is has anybody used one on saltwater? I want to set one up and just need know if will work the same way as freshwater.