I do think that with LARGE water changes that skimmers are less necessary, but I also wouldn't consider 10% weekly a large water change... just IMO. Large would be somewhere in the 30%-75% range. I personally like and practice 50% total water volume changes every 2-4 weeks myself, but I run a skimmer too.idog said:If you keep up with large water changes like 10% weekly, then you really don't need one. For larger tanks they are necessary, but nanos can be kept without skimmers if you follw a schedule like this.