Well here is my thought after using Zeovit on my last setup prior to moving and tear down. The system can work. It is overly reliant on adding stuff and shaking the stones, ect. So if you end up being away more frequently, they system breaks down quickly and you will strip everything from your tank.
That being said, the number 1 lesson I learned from Zeovit is:
Spend 5 minutes with your tank every day. Not for pleasure or playing with some setting, but really looking at each animal. Learn to understand what they need when they don't look like they did the day before. If you hold to the zeovit system, the biggest thing that improves the tank is your new regiment for better husbandry than you had in the past. It forces you to spend time every day knowing your tank and how to care for it. I thought it was worth the cost because it taught me that just a few minutes every day improved the quality of life in my tank 10 fold.
I do not use Zeovit any longer and will not. I take too many work trips these days and the nutrients would be consumed and bottom out in my aquarium before I could get them back to healthy levels. I do spend about 10 minutes every day intently looking at each coral, each fish, each piece of equipment.
Not arguing here but if you have a reef tank you spent more than 5 minutes per day just looking at the tank.