[Simons]

My thoughts are no matter how good, efficient or over sized your skimmer is, it will never be 100% affective in removing all organics.

Most people that I know who run tanks and do small or no water changes also usually have a very low bio load, AND they feed sparingly.

If you think from a closed ecosystem perspective, when living organisms are present they introduce waste. Yes carbon, GFO etc help in that removal but they are never perfect.

I think toxins, nitrates etc build up over time in all tanks, just some build up much slower than others (bio load, feeding habits play a huge role in that department) but eventually levels will build up.

The advantage to very slow build up is anything alive has more ability to adapt over the longer period. So I don't see it as 'never needing' but perhaps needing less frequently but still needing (to do water changes).