You mean overstocked tanks with tangs and angels or other aggressive eating fish....
You mean they do nothing but top off in a 5 and 6 month period and still manage to be able to grow acros.....
Not necessarily large but 180 gallon tanks....
I have yet to see this....Not saying it's not going on, but I just never heard or saw this going on....
If you keep acros you should be doing frequent water changes regardless of nitrate levels to replenish trace elements.
I think you will be hard pressed to find anyone who successfully keeps colorful acropora and goes 6 months w/out a water change, nitrate reactor or not.