Can you help me understand why my SPS corals are bleaching?

Can you help me understand why my SPS corals are bleaching?
I'm a couple months into SPS.
I've lost a green stylo already. Now have a birdsnext whiting out and looks like my purple stylo starting too.
I upgraded my LEDs to Kessil 360Ws and running at about 30-40% intensity. Doing it lower intensity to not fry my corals because last LEDs didn't have UV. Maybe that's the issue.
All sps up high with good flow. Master levels are below.
My montis are doing great

PH 8.2
Ammonia 0
Nitrate 0
Nitrite 0
Calcium 500 (I don't dose calcium. Naturally this high)
Magnesium 1250-1300
Alkalinity 8.2

What are reasons for SPS to bleach? What can I do to stop it?
Thanks


My 2 purple stylos. One on right is thinning out.


My birdsnest. Bottom is bleached and rest is thinning


Picture of tank so you can see their placements


Further back to see distance of lights to corals

 

Move them down or lower the intensity more would be what I would try. I would also get a phosphate level just in case you're seeing browning rather than loss of color. Is this a ultra low nutrient system?

Stylophora has always been a sensitive coral for me.

Tank looks really nice BTW.

 

I would say yes to low nutrient. I don't have a 'frug just a basic sump.
I'll move the lower tonight. Thanks for the reply and compliment on tank. I'm proud of it but so much I don't know. Like is nutrient needed for some SPS?

 

Yeah you can not starve sps they do need some DOC (dissolved organic compounds) or out right food particles.

Although research scientists had established that symbiotic algae (Symbiodinium spp.) could the supply most if not all of the daily carbon requirements of the invertebrate host, this was construed by many to mean that feeding wasn’t necessary, hence the necessity supplemental feeding of corals in captivity was much in doubt by many.

Dana Riddle
http://www.advancedaquarist.com/2014/11/aafeature

And below:
So, it would seem that if a little light is good, a lot of light is better. And this is where two debates among hobbyists rages for quite some time (and are still issues for the uninformed hobbyist). These concepts are unfortunately still circulated among hobbyists: 1. It is impossible to exceed the amount of light found on natural coral reefs and 2: It would be beneficial to corals and their zooxanthellae even if we could achieve (and even exceed) that much light. The truth of these matters: It is possible to exceed the amount of light corals receive in nature and it can be harmful.

So I posted the above, as I do believe you have to feed corals and that we capable of over illuminating some of our corals.

 

well all I know is some of my bleaching issues were caused by low alk issues. 8.2 I would say is a bit low. I would think you should shoot for 10 to 11 range minimum but just an opinion. This would also help decrease you calcium level slightly.

Although I used to run a tank at 500 calcium and had no issues.. but it was a massive mushroom tank(oh how I miss that tank).

That birdnest is that a green tip? I had bleaching issue with mine and move it to a corner of tank with decent flow and mine is thriving.. Light and flow definitely played a factor in this 1.

I am still trying to bring back my pocillopora but that has started to color up since I have started to track and dose ALK, PH, and now calcium. Still working out kinks but it is much happier with ALK increase.

 

I just read this article today, it is still sitting next to me on my desk.

 

Just to add to the other great ideas, what is your tank temp, and is it stable? In nature, a temp increase of only 2F can bleach corals if sustained for an extended period; an increase of 6F will bleach them almost immediately.

 

I'd say lighting is your issue with the upgrade to Kessil and all. Hows the rest of your sps, seems like you have a few others, yes?

 

I would double check those test results.

 

What type of light and output were on their before?
How deep is tank and how far above was old light and how far above top are the new lights?
How long ago did you upgrade your lights?
Think hard were there any signs or hint of bleaching with old light? How were there color before the light..faded at all?

I would suggest that you check out unique corals as I know they were running kessil. I believe somewhere it says how high above they keep their lights on particular corals.
You might even want to try to PM them.


Problem with bleaching is there are a variety or plausible causes.

With the gooseneck on the kessil you are slightly limited to placement of the light as far as height goes.

Mike Rice also has kessil on his tank so you may want to ping him to see what levels he runs his at and height. Make sure you aks height to top of water and to bottom. Confirm his tank height against yours.

Is that a your stable ALK or does it fluctuate alot?

Are you doing any dosing?

may find this article interesting
https://reefworks.co.uk/articles/obtaining-the-best-colours-from-your-corals/