How to tell what causes bleaching?

[91Atrac]

Hey guys

So to explain a bit better Im running 4 par38 HALO lightboxleds over my 40g cube with 60degree optics.

I have lots of mixed coral but mainly sps and zoas/palys.

My question is I have a question on bleaching. I have a cactus coral on the sandbed that was brown for awhile as it usually is but started to bleach apparently. Best pic I can get is what's posted. I have zoas near the top and wondering if the poor par value might be what caused the bleaching even with the total watts per gallon.

I can't be sure on my parameters so I do apologize for those asking about it cuz I have never tested aside from cycling. I've learnt to watch from the coral and not much from water.

Well... Tell me your opinions.

OH! Lights are set to front 2 are 30" from bottom of the tank and 35" roughly the back 2 lights.ps ignore the 3 frags of birdsnest and candy cane as I'm recovering them for a friend and JUST received them

 

[AcroporAddict]

I am not familiar with bleaching from a lack of light. Your Pavona does not look bleached to me, unless all the blue in the pic is doing something to the appearance of your pic. I could not see any bleaching in your tank from what you posted.

 

[91Atrac]

Yea blue does throw off the white it's getting. My blue tenius isn't quite as blue as it use to be as well. But still. So odd. Also that's why I was wondering if poor PAR value causes bleachjng

 

[AcroporAddict]

The Starburst Monti looks really good, as does most everything else, at least to me.

 

[91Atrac]

Yea I agree!!!! That's why I'm confused as to why it's looking like it is.

 

[Vucious]

So you can bleach with low or high light?

 

[Timfish]

"Bleaching" in corals is loss of the golden brown symbiotic dinoflagellates (zooxanthellea). It can be caused by any change in environment a coral specimen does not like, too much light, too little light, temperature too high or too low or lack of enough nutrients (nitrogen, phosphate) to grow their symbionts. Additionally research has shown corals in the wild learn their environment and two examples of the same species may bleach under different conditions, Abstract for one paper is here: http://www.researchgate.net/publica...e_susceptibility_of_a_reef_coral_to_bleaching

 

[91Atrac]

Thanks for that!! Great info!