Cheato has been fickle for me. I think maybe there is too much competition for inorganic nutrients in my system. I have 15 decent size fish in my 90 that are fed very well. I can't imagine that there isn't quite a bit of nutrients flowing through the system. I've tried dosing iron, potassium. changing lights, adding flow, and even played it a little Aerosmith for a while. Nothing made it grow. Well, wait... it did grow while I dosed the nutrients I wanted it to bind! I finally gave up, threw away the light, and replaced it all with live rock and live sand.
I think the bacteria, sponges, tube worms. and other "cryptic" life that proliferates in dark fuges helps manage nutrients, be it in a different way, without the need for lights, harvesting, and etc. I know that life occurs under the rocks in lighted areas too, but we tend to use less rock in the display tank now. More in the sump/refugium is surely a benefit.
I know that little N&P is actually bound in the organisms themselves except for the amount bound in growing tissues. However, I think the cryptic organisms help the nutrient control process by converting organic nutrients so that they can be used by other organisms in the system. That's about the extent of my reasoning and knowledge though.
