Monti cap bleaching

[ced]

All the monti caps I got for my tank will start bleaching after a few weeks, despite all the other rank inhabitants doing well.

Anyone has any clue why?

I experimented all types of bleaching:
fast (overnight), progressive and slow (over a few weeks), starting from the edge, starting from the center etc....
On the other side, the tridacna clam, the finger coral, the RBTA, the frogspawn and the brain coral are doing very well and growing.

Numbers:
9 months old tank, DSB
40G tank + 20G sump/refugium
Urchin in-sump skimmer
mag9.5 return pump
150W MH (14.5K) + 2x65W 50/50
Temp: 82
Ph: 8.4
ALk: 3.5
Calcium: 400
Mag: 950
Nitrate: 0.5
Phosphate: 0.1
Fish: clown, chromis, bangai, mandarin

 

[examiner]

Bleaching? (meaning they are still alive but pale/white color).....or tissue necrosis (meaning death)?

Your mag is pretty low, and that can lead to problems maintaining alk/calcium balance (though yours doesn't look too bad). How stable is your alk/calcium, and how do you maintain?

Do you have any other sps that you are successful with? What is your in-tank flow? Is your temp steady? How close to your MH are you placing them? Are you getting them from fellow reefers who have acclimated them to captivity?

100 questions I know, but all pretty necessary to figure out the problem.

 

[ced]

I am maintaining ALk/Calc with top-off Kalkwasser (+ vinegar).
So far the other SPS I have is a finger coral.
My in tank flow comes from the return pump(mag9.5)+SCWD - around 800G/h.
The tank is a 40G wide (so not deep), and the cap are halfway and just under the MH.
Half of the cap came from reefers, half from different lfs.

 

[examiner]

Are they dying or just bleaching?

Caps *generally* do best if placed off to the side of the MH "hot spot" (although they can be acclimated to high and bright in the tank). You may just be blasting them with too much light too quick.

Not sure what coral you are referring to with the common name "finger coral". If it's truly a sps and it's doing well, that would tend to rule out most water chemistry issues.

Your 20X tank volume flow is going to favor a LPS/softie tank. Not to say you won't be able to keep sps, but they would be happier if you would double the flow (at a minimum).

That's about all I can offer, hopefully someone else will chime in. If you decide to try another one, I'd start it at the bottom of the tank and off to the side, and very gradually move it up to where you want it to be. I'd still encourage final placement somewhere off to the side and not directly under the bulb. Good luck!

 

[ced]

Thank you.
Well, all I can say is that they are turning white.
When I introduce them to the tank, I start to put them at the bottom and off the side for a week.