Coralline algae bleaching...

[fishzen]

Hi All,
As you can see on the picture, the coralline in some of my tank's LR is bleaching. I've got no clue on what's happening. Can somebody help?
Tank: 20 G
Lights: 135w PC
Inhabitants: 1 Percula clow
1 Fire shrimp
blue legs and snails
Water params: PH 8.2
AMM 0
Ntri 0
Ntra 0
Cal 400mg
Temp: 76~78
Thanks.

 

[reefnut]

Any recent lighting upgrades or bulb changes?? Also, have you tested your phosphates??

 

[fishzen]

Thanks for your reply.
Did change the bulbs a couple of weeks ago, however the bleaching has been happening in the last 5 or 6 months. Phos reading is at 0, I don't know how exact is it.
I feed the fish twice a week with formula one. Water changes are done with RO water. Lights are on between 7 and 8 hours.
Thanks.

 

[speg]

Any recent temperature increases/decreases..? Did you install a heater for the winter?

 

[reefnut]

Originally Posted by fishzen
the bleaching has been happening in the last 5 or 6 months.
On this rock or through out the tank?? What is your alkalinity and calcium levels?? on top of Speg's questions??

 

[dill]

I have had this happen, I always thought it was some sort of cycle, I take a piece of live rock with good groth and scrape it with a razor under water in the current to re seed...

 

[fishzen]

To answer your questions;
Speg.
No recent changes in temp. I haven't install a heater for winter, we are still at above 80o in Florida.
ReefNut
Calcium is at 400, Alk is at 230, I bought one of those test strips for Alk and hardness, I do not think they are reliable, but until I find a more accurate one that is what I've got.
The bleaching is happening on many rocks throught out the tank. I was looking last night to one spot on another rock that lost all of its coralline and it seems to be comming back with a nice pink color.
Dill
you could be right on the cycle observation. Although the tank has been up and running for 4 years. In order to re seed is it better to do it with a razor or with a tooh brush? I do not want to hurt my already week coralline.
Thanks for your input.

 

[speg]

>NOW< the temp is above 80 but a couple weeks ago it was decently cold (for FL). Is it possible that when that cold front came through due to the hurricane it caused temps to decrease in your tank?

 

[fishzen]

I don't think is a temperature issue, the bleaching is been happening for the past 5 or 6 months (as stated above) even with the past cold front my tank had no change on temp.
I am going to keep monitoring the spot on an already bleached rock that is showing new coralline growth, in the meantime I will try to raise the calcium level.
Thanks.

 

[tizzo]

Fishzen, I hafta ask. Do you have a lot of those little asterina stars?? Cause I do and they do that to my coralline. I don't know if they block the light or actually eat it, but if you look real close you can actually see the outline of their shape left on the coralline. Mine is not "bleaching" so to speak, but rather getting very dulled all over uniformely.

 

[fishzen]

Haven't seen one of those or copepods in my tank in ages....so that might not be the issue either.
This is baffling me

Thanks.