bleaching question

[whitetiprs]

With in the last two days I have noticed all the corline algae on the back wall of my tank bleaching. Also my green slimer frag has appeared to bleach only on the top and the bottem of the branches look normal. And two other acros both high up in the tank have some bleaching on their tips, one unkown and the other is a bottle brush. All of my other corals look normal and have good PE. What could be the cause of this?

I started adding kalk last weekend but stoped on friday when I saw the bleaching. Not sure if that could have done it I tested everyday before and after adding the kalk but did not notice any significant changes in pH, calcium, or Alk.

I upgraded my lighting to 2x 250 watt corlvue 14k MH about 2 months ago and acclimated everything with screening for a month so I don't susspect that to be the problem.

I just preformed a 10% WC and here are the current test result:

Calcium: 360 ppm was 490 on fri when stopped adding kalk
Alk: 3 meg/l was 2 meg/l on fri
ph: 8.2, was 8.3-8.4 on fri
po4: 0
no2: 0
no3:0
NH3: 0-0.25 recently had a six-line die for unknown reasons, 2-3 weeks ago
Salinity: 1.027
Temp: 82-84.5

Any Ideas?

 

[Sk8r]

I had a coralline bleaching event when a heater sent my tank to 85 or over. Fortunately I stopped it fast (within hours) and lowered the temperature slowly back to 76, where it mostly stays. The coralline peeled a bit, like sunburn, then began to recover. After 4 weeks it's back the way it was except for the top of a couple of rocks. I didn't have SPS at the time (the tank was new) so I can't answer to its response, but I'd be very suspicious of a temperature event, maybe accelerating chemical reactions: chemical things do run faster when it's warm.

 

[jsweir]

Anything causing your water clarity to improve lately? Filter socks?

 

[whitetiprs]

The only thing that I can think of would be I changed out my Rowaphos media about 3 weeks ago and cleaned the algae out of my overflow last week. I change carbon and clean all sponges and filter pads weekly as well as doing a 10% water change. The only real new thing I am doing is using kalk.

 

[jsweir]

Did you say sponges? What kind of filter are you using? Adding kalk will cause your ph to swing - you notice any change in ph?

 

[whitetiprs]

Yes the I should be more specific, the sponges I am refering to are the prefilters on my mag 3 and mad 5 pumps. One for the return and one for the skimmer. And also the poly-pad I wrap around my carbon bag, which sits under the overflow into the sump. I am running an Aqua-C urchin w/ mag 3 plus a refuge w/ chaeto, mangroves and rubble. I did not notice any changes in pH before the bleaching occured, if anything it is more stable with the addition of kalk.