SPS randomly turning white

[phish guy]

I have been having a problem with my sps as of late. what will happen is, i will have my sps growing from a frag, fully heal and start new growth, then all of the sudden, the growth comes to a hault and the frag starts to turn a chalky white color and slowly die off. now when i say chalky, i mean that it has some of its color to it, but starts to slowly turn chalky white and then into its skeleton. the tissue does not recede. the frag just gets powdery looking. i try to move the frag thinking its getting too much light, but the process continues. Not all of my SPS are effected by this. all of my RED sps are fine, my birdsnests are fine, and my pocillopora are fine. but my monticaps other than the red ones and acros, recede their polyp extension, then the whiting process occurs. all my zoas and palys are great, LPS are loving life, and my 2 big Derasa clams are doing well also. here are some of my tank details

I have a 150 gallon RR tank with refugium, reef octopus NWB250 skimmer, vortech mp40, koralia 1400, 925 GPH eheim return, 150+ Lbs live rock, Aragonite sand, 2 reeftech LED Fixtures ( 205 watts per fixture- royal blues and blue on at 100% and cool and warm whites on at 55%)high capacity gfo, ROX carbon running 1 week a month average, and monthly water changes. i does BRS 2 part everyday and it keeps my levels at 400 for calcium and 9 for DkH. my phosphates read at 0 on the hanna phosphate colorimeter, nitrates 0, PH 8.2 with a pinpoint reader, Salinity @ 1.025. the only thing that i have changed to my tank recently was that i had the lights sitting on a piece of wood until i hung them, then when i hung them, i made sure they were the same height as they were on the wood. i honestly am confused right now and any help would be greatly appreciated. thank you!!
andrew

 

[captjab]

How long have you been running LED's? How much GFO are you running and are you running it 24/7, or is it on the same schedule as the ROX?

 

[sahin]

I experianced this sort of issue with my SPS some time back on a previous setup. The setup was about 6 months old, and I would have some of the SPS turn dry looking and fizzle away. NO RTN/STN; but the tissue would become thin and dry looking and eventually the SPS coral dies. Not all SPS were affected.I did put it down to a lack of nutrients. My phosphates measured 0ppm on my Hanna ULR Photometer. The problem did resolve itself after some months. I increased feeding; but also the increased frequency of water changes. I was using KZ Carbon at the time. I think I stripped the water too clean. I stopped using GAC as well.

 

[phish guy]

It may be from the tank being " too clean" I haven't run carbon in a long time and my skimmer is pulling out somewhat clear water. Would Increasing water changes allow nutrients to build up or just pull them out again? I guess I need to dirty up the tank

 

[sahin]

It may be from the tank being " too clean" I haven't run carbon in a long time and my skimmer is pulling out somewhat clear water. Would Increasing water changes allow nutrients to build up or just pull them out again? I guess I need to dirty up the tank

I was at work when I made my first post; just wanted to make sure that you've done the usual checks and double checked the main parameters; Salinity, CA, Alk, Mg, temperature etc etc?

And checked for pests etc?

If all above checks out fine, then I would do the following:

1. Suspend GAC for at least 2 weeks and check for improvement.

2. Feed the tank and fishes more; BUT DONT STOP doing water changes. Keep up at least 15% regular weekly water changes.

The trick is to increase feeding; without letting the extra food rot and decrease water quality. So whilst you do increase feeding, up the water changes by at least 5% per week for at least a few weeks to see if the extra feeding helps.