If you are dosing your tank or adding top off water w/kalk, make sure it is in a return chamber after the chaeto. I use Power Glo Florescent lights on my refuge, they are only on about 8-10 hours at night when my tank lights are off to reduce temp. and ph swings. I have been skimmer-less for a few months now, but my chaeto did fine with the skimmer too.