Zeovit isn't necessary, but it's fun.
I will say this: the water clarity I got with Zeo was unparalleled with anything previous I tried, including denitrators and ozone. The difference in water clarity truly caught me off guard. I feel the water was far more polished looking than with anything I've tried previously.
The use of Zeo allows me to increase my margins: I can feed more to my livestock than I would be able to without, and not hopefully not worry about NO3 or PO4 running away on me. And I don't need to run GFO, so that helps. And it has the benefit of feeding the corals as well.
So, I'm happy with Zeo, and plan to continue with it. I'm a total newb at Zeo though, I'm only one month in.
But, it's not a limiting factor by any stretch. There are nice SPS tanks with Zeo, there are nice SPS tanks without Zeo. It is therefore not a critical path or limiting factor, but just one tool that one can employ out of an arsenal of tools or methodologies. As with many other things, it's not what's right, but what's right for you that counts in the end.
