I have a 75 Gal saltwater tank that has been fishless for about 18 months. It has about a 1 inch aragonite sand bed. Built in overflow with a 15 gal sump. I would like to change the tank over to a African Cichlid tank. If I drained out the saltwater would it be ok to reuse the sand bed?? I know there would be a little saltwater left in the sand but with 50-60 gal freshwater the salinity lvl wouldn't be much. I know the tank would have to go thru a new cycle. Is there a way to use the sump for filtration instead of buying a canister filter?? Thanks for any help. I am just trying to get some ideas.