Bleaching and some died corals

[joeang]

I am at a major stump right now, all of a sudden in the past month I have had several corals die and more are bleaching. I have been in the hobby for 10 years and several thousands of dollars in equipment. If you name it I bet I have it. But this has me baffled. I have a 120 gal tank with a 75 gallon sump and a 29 gallon ref all tie together in a loop system. My lights are MH 250 watt, my perameters are as follows cal 440, alk 8.6, mag 1250, sal 34.9. Not sure of what more I need to pass right now please ask questions. Thanks for any help you might have. By the way I have a Apex DOS pump that does 3 gallons of water change everyday and once a month I do a 20 gallon water change too as per Neptune's recommendation.

 

[vhuang168]

What kind of corals died and how did they die?


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[joeang]

They are my SPS acro they started to bleach out and then they started stn from the bottom and now the tips are starting to die.

 

[NaturalReef]

My past experience with sps bleaching......

Check..

1) Alk swings
2) sudden nutrient change to ulns i.e.....biopellets ,gfo etc.
3) ulns without acclimating coral to previous lighting intensity.
4) Flow changes i.e....lost $1500 in sps to a maxspect gyre that failed
5) stray voltage
6) equipment failure i.e dosing pump adding too much or not enough and alk issues.
7) salinity issues with auto topoff failure....
8) Temperature swings from faulty heater/controller
9) chemicals from sprays near the tank or tainted hands

Throw some good quality carbon in to rule out toxins. Lower lighting if its already set high or slowly increase intensity if lighting is already low. Water change will also help. Let us know what you find out.