not very many critters will live too long with a 24 hour schedule. every thing needs a little bit of a break. if you think about the natural habitat where most of the animals come from (except the turbos), they are used too a very long light cycle, just not too intense too soon which is why we have to keep our halides time so small. i personally have a pc on my refugium and have it timed for 16 hrs, just to over compensate a little for the lapse in time/ph fluctuations that might happen. if it is a more natural lighting you can keep whatever you like, just so long as they do not release any toxic chemicals. as i am sure you are well aware, the point of a refugium is to provide a safe haven for other animals (copepods, amphipods, any other pod or various inverts) to live without being eaten, otherwise you just have another tank, right? so why keep carnivorous animals there? i personally keep the live stock very limited , and just do the work that they would do myself. it just helps to limit the hungry animals you have that are taxing your system and producing waste. do not get me wrong you want to brake down the nutrients the best that you can which is why you have the caulerpa and other fast growing algae/ coral. keep it simple and work at the hobby that is why it is a hobby. i am not trying to preach. that is just my 2 cents.
