Hey BB
sorry to hear you are still having issues. Do you have a deep sand bed? This could be the source of your issue. Fill a beaker with fresh saltwater and dump some sand from the tank or sump. Let it sit overnight. Test it for nitrate. If you get a reading then that is the issue.
sorry to hear you are still having issues. Do you have a deep sand bed? This could be the source of your issue. Fill a beaker with fresh saltwater and dump some sand from the tank or sump. Let it sit overnight. Test it for nitrate. If you get a reading then that is the issue.