I use two icecap 1k in a frag system. I don't think they are noisy, but I have other noisy stuff in that area. If the noise is only on the higher setting, or transition period, may want to consider using a real slow speed in the day, and ramp up at night (if you have a controller). This provides a gentle flow with less agitation to the polyps as they soak up the light and then hit the dead spots at night to remove detritus.