gsp turning white

Has anybody's done this? All the polyps still open but 3 separate colonies in different areas of the tank are all turning white. They all started from the same colony I've had for about a year or so now. All other corals look great. They used to be a beautiful fluorescent green. You can still see the green tint in them with the T5's or LED's on but look bleach white when the MH kicks on. Any ideas?

 

Too much light, they have ejected the zooxanthellae because they are getting too much food from it.

 

Whats your temp? and how close are they too the light? and what are your params?

 

All params good. Ammonia, nitrate, nitrite, all 0. Ph 8.1. They are in different areas of the tank. Some up high in the tank maybe 8" $rom the light or so. The biggest colony all the way down on the sandbed. Light schedule has been the same since I've had them, over a year now. Temp is 79 as always. They just started turning white over the past week or so. Weird...

 

Yeah, it is weird....idk...I would google it lol

 

Any other ideas?

 

So I still haven't been able to figure this out. Been doing a lot of reading but only found it could be too long of a light period, too close to the light, or a newer brighter light. None of which are the case. I know its not a lighting problem. Even in some areas where the mat has grown under a rock where the polys receive little to no light at all are still bleaching.
Anybody have any other ideas? The white is really ugly .

 

Did you check your magnesium level?

 

MG/alk/ca can cause stress with can lead to bleaching, as can temp swings, current, and metals in your water. Start by testing the big three, then knock down the rest. I agree its probably not light. Something changed lets find it!

 

nutrient level and/or light is most likely. Its ether getting way to little or way to much.