Live rock bleaching

[jsker]

Thank you. Also when your ph is low what do u use to raise it? I hear opening a window is good but what do u suggest?

here are a couple of articles that will help you with raising PH
link
link
Check your alk also, Running low alk can cause PH issues. FYI a PH of 8.0 and above is fine.

 

[Y2KReef]

How long have you had the rock?? Looks like shock.

 

[Ncreefer]

Been in my system a year. Guy before me 5 years

 

[0202chunky]

Umm it's been like 3 to 4 months.

 

[cbutkos]

Do a little research on raising cal, alk, and mag. There are plenty of good articles. The chemicals needed can be found at home depot/Lowes and are easy to mix. Or you could just buy them from brs or whomever. If I remember correctly raise mag first slowly 200ish ppm should get you in the right ballpark (decide on whichever number you want to achieve after your research) then go for alk and cal. This may or may not have anything to do with your coraline issue, but if you just did several water changes and your numbers are still low you're likely going to have to start dosing to keep alk and cal up.

This article has good info on the big three
http://reefkeeping.com/issues/2004-05/rhf/

There are links in the article to others that will be of use

Good luck

 

[BluewaterLa]

Coralline algae incorporates a significant amount of carbonates and magnesium into itself.
Magnesium is important to it's growth and health just as calcium as DKH

Low calcium levels will mainly keep it from growing much if at all one established
Alkalinity on the other hand can cause it to do what you are seeing just as a swing would cause damage to sps tips or tissue loss if it drops to much or fast

Another thing would be a change in light
Most coralline likes lower light levels and can bleach or not grow at all in higher intensity lighting
Though there are some varieties that like the intense light

Was the rock covered in any algae for a significant amount of time ?
I've had coralline die off from being covered with algae even for short periods plus the other reasons listed above

If your lights havent changed recently and it's white like that over night I would suspect water chemistry to be the cause.
Much like corals it too can take a bit of time to finally kick the bucket slowly or very quick.