I think PURA complete binds the ammonia to the media or something like that... So removing the media is enough... As long as you get a increase and decrease in the Ammonia and Nitrite level.. It is cycling normally..
My concern is the constant large amount water change will reduce the tank capacity to cope with ammonia and nitrite when you add livestock although the amount of bacteria in the new salt mix is quite high but as the time goes by the amount of bacteria decreases... So it is better to observe for a week and go slow with the stocking...
Just to confirm that the tank is running fine, dun add the fishes yet.. And moniter the parameter for a week first...If nothing goes wrong, you can proceed to add the fish... what you have now?