New Bulbs causing Acro bleaching

[karlseith]

I just replaced the bulbs in my Current Sunpod 500w MH fixture and ever since my Acro's have not been happy. The bulbs are two 250w 14k MH's (same as before) hanging over a 72 bow. The old bulbs were something like 2 years old and there is an obvious change in visible temperature between the new and old bulbs as I kind of expected from MH's that old. The tank is roughly 8 months old and the Acros have been in the tank for about 5 months doing very well, with fully expanding polyps and noticeable growth. They are mid way, to 2/3's up the tank with good water flow. Some of the tips are bleaching and some polyps are not expanding fully. Do I need to move them? If so, up or down?? I guess I'm confused why new bulbs would have such a dramatic effect on healthy coral. BTW nothing else has changed in the tank, temp., pH., alk., etc... Any ideas???

 

[Bige]

The new lights could do this. You can raise the lights and slowly lower. You could reduce photo period. You could also put window screen over tank in layer and remove layers each week. So the mh were 2 years old? Next time you could replace the bulbs after six months so the coral aren't subject to the drastic light change. This is common with any light changes.

 

[Gregcoyote]

I second that opinion. The corals were use to the spectrum the old bulbs were putting out. And at two years, they were not putting out nearly the PAR they did when new. Your corals need sunglasses! Mesh over the tank will work nicely.