Please elaborate? A friend on here did get rid of his skimmer and doesn't do water changes for over a year while relying on his SM ATS. I went 2 years without a water change and 1 year with the skimmer offline on a 10 year old mature tank and the nutrients stayed low. This tank is 2 months young. I feel that the water changes are a necessity at this point until that coraline takes hold.Ok, excellent. I've been doin this for a while and can't help but think you have been duped, like others.