Too many fish for a 65G plus they range from peaceful to very aggressive. The 'peaceful' clowns are eventually going to cause trouble, the tang shouldn't be in there and the cream.. well.. that's a mean fish when she's in a tank the size she needs. In your tank.. look out brother..
So between the filters (and the possible mechanical media involved), the feeding and the waste in 65g's of water.. Be quite the chore to keep those nitrates down.
BTW: There's only 2 ways to decrease nitrates.. water changes and anaerobic bacteria. Those additives at most help remove the DOCs which will eventually turn into nitrates but they don't remove or reduce what you have