We are modding our w/d filters on our 55g and 110g tanks by removing the bioballs and adding small fuges in the compartment where the bioballs would be. We are looking for sand to create a small DSB in each one. We have been struggling with the Nitrates like crazy to no avail. After gettin all bioballs out we are seeing the nitrates lowered quite considerably! YAHOOOOO! Just let me know if you have any to get rid of, how much and how much you are asking for it!