I bought some Aztec Sundial zoas at an LFS a few months ago. They're my favorite zoas of all time. I had them 6" under my 110w 50/50 PC in my Red Sea Max but three months ago I moved them 2ft under the 150w 14000K halide in my BioCube 29 HQI. I acclimated them to the halide with 4 layers of window screening over them and removed one layer at a time over a two week period. About little more than a month ago I noticed them becoming lighter in color. They've seemed to bleached a good bit more since then. They've been creating baby polyps since I put them in the BioCube 29 HQI and they've more than doubled their colony size. Today I looked at them and saw the main polyp expelling zooxanthalle, which is when I got pretty worried. I don't know what is causing them to bleach or how to help them. I've had 8 layers (3 fold-overs) of window screening (which surprisingly doesn't dim the light very much) over them for the past month because I was worried they may be getting too much light. It may have helped slow the bleaching down but they're still bleaching. Another thing I've noticed is that their skirts were fat and rather short at first but as the zoas bleached the skirts elongated. The column of the zoa is bleached as well as the oral disc. There are Red Hornets and Purple Hornets in the tank with them that have really colored up since I put them in and they're doing pretty well as of now. Aztec Sundials before bleaching: Aztec Sundials after bleaching: Parameters... (test dates vary in the time frame of four days ago and yesterday) dKH - 10.9 Ca - 510 Mg - 1410 pH - 8.2 Salinity - 1.023 Temperature - 78F Nitrate - 0 (I just got it to 0, but it wasn't too high, just high enough for a bit of algae growth) Phosphate - 0 (I just got it to 0, but it wasn't too high, just high enough for a bit of algae growth) If you need any more info to help diagnose the problem let me know. Any advice is greatly appreciated. Thanks in advance!