I too have experienced massively gross smelling fish water from my zero water filters/water! It's fine for 2-3 weeks after you change the filter, but after that it starts to smell bad.
So it registers zero contaminants, but the smell is horrible and I'm afraid to drink the water at all. I threw away the whole filter away 2 weeks after I bought it, and cleaned the empty pitcher etc, thoroughly. I then replaced it with a brand new filter. After two or three weeks passed, again we were hit with the same fishy smell.
Because it can come in gradually, we were rudely aware of the strong fish tank order all at once because I used zero water in a pot and brought it to a boil for pasta. The entire house filled with dead fish stench so badly I had to open it all up and use candles, incense and fans. I couldn't believe it was doing this again. I tested the water for contaminates it says 0 I tasted the water it was horrible and honestly I felt a slight burn on my tongue and throat.
Very scary! I threw my entire system in the trash.
I don't know what's wrong with this system but I'm not willing to experiment any longer. It's not worth our health!
Product or Service Mentioned: Zerowater Water Filter.
Reason of review: Bad quality.