Im not to sure about all of you, but the water here is horrible. I have a 10g set up as a QT for feeders, and even they can't live in it without me adding some type of water conditioner. Goldfish are pretty hardy and if they can't survive in untreated water then I wont take the chance of not treating the water on my other tanks. My dude down the road owns a 125g African Cichlid set up, Hes had to come over my house to get a bottle of prime because he forgot he ran out and his fish were dieing due to the water change he just did.