Hmm. I guess I'll try this as well as I'm also running Triton and don't often do water changes. I don't want to get into any "full-throated debates" I just want to be able to grow some SPS LOL. It's amazing how much is going on in the tank particular and in this hobby more generallyTrimming Chaeto regularly definitely helps encourage new growth and reduction of nutrients better than if left untrimmed IME. I've run Triton tanks for a few years now and experimented with trimming and not trimming. If left untrimmed the chaeto will eventually grow into a thick mat that inhibits new growth and nutrient removal abilities. At this point the chaeto will start to die off partially and make an absolute mess as it disintegrates. Eventually enough will die to allow new growth and the cycle will continue of growth / die off. So yes chaeto is self-regulating, however it's messy and does not provide optimal nutrient removal when left too its own accord. I now trim my chaeto about every 2 weeks to keep it somewhat loose and growing fast. This provides both better nutrient reduction capabilities and also prevents die backs which are messy and clog pumps / sump teeth. For maximum nutrient reduction you should let the chaeto grow as large as possible to fill the fuge space but not to the point that it starts to mat up and get super dense.