I would worry alot more about the current health of your fish right now, than how quickly you can get your tank to cycle. You've made a mistake and added too many fish to a tank that is not ready. Yes the zeolite will leach ammonia back into the water eventually as for delaying the cycle, I would debate this. But what it will do right now is remove excess ammonia from your tank. As I said in previuos post once the ammonia problem is under control remove the Amrid and put in more bio max.
It is not going to be easy there is no magic cure. You've spent alot of money one these fish and thier health at the present time should be your main concern. Do as recomended in post #8 and you will get through this.
As for the filter, I am currently running a Emporer 400 on a 75 gallon tank which I do a 40-50% water change weekly. It is stocked with a 13" silver aro, 6" gourami, 2x 5" rapheal cats, and 20 to 30 1/2" convict fry. This bioload is more than what you currently have. My water params BEFORE the water change are 0 ammonia, 0 nitrites and nitrates of 20ppm.
Ideal water conditions. Your Ac110 is comparable to the Emp400 if not better. I would not worry about another filter at this time.
Of course I am assuming that your discus and ray are still small, eventually you'll need to move the ray, but the Discus will be fine in that tank.