Dying acros : help needed

[perikaruppan]

Dear friends
I am having a 400 gallon SPS Tank with mostly frags and some wild cultured SPS. All the tank parameters are stable.
Alk at 9.6, CA at 420, MG at 1350 nitrates at 5, phosphates at 0.03.
I have been noticing on a few acros that the bases started to turn white and thought they were STNing and looked but there was slime on that area so they were not STNing.
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And in a few days it started to spread faster and now it is like this
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So thought it might be AEFW and did a revive dip (40ml of revive in 1 gallon, used a good pump to blast the corals for 15min and dipped in tank water again) and found NOTHING no dead AEFW nor was able to spot any eggs on the acro. This is what I found
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Only some tiny dead pods and dirt.

So unable to determine what the problem is.

I have two flame Angels that go nipping on a few corals - especially Montis and also these corals as they are receding. So can it be the flames?

Or I had replaced the DIY LEDS recently with some Chinese bought CREE LEDs - can that be a reason?

How can I diagnose the problem further and arrive at a solution?

I have nearly 84 specimens of various acros and Montis in my tank that I wanna save. I have collected them over a period of few years.

Kindly help.

Peri

[kenjung]

Are you running bio pellet ?

[MisterP]

Do you run GFO?

[perikaruppan]

I am running GFO not bio pellets. My GFO is about three months old. So going to replace it today. Can that be the cause also???

[UTCReefer]

How is the PE in general?
Any sliming or receding at the tips?

[perikaruppan]

I am running GFO not bio pellets. My GFO is about three months old. So going to replace it today. Can that be the cause also???

[perikaruppan]

PE is not that great on a couple of them but in one acro-garf bonsai is very good with color. Not much sliming on any. But when taken out there is which I feel is normal

[MisterP]

Well if phosphates are 0.03 maybe the GFO is still OK. How often do you typically change it?

How many fish do you have?

How much do you feed?

What is your feed schedule?

How long have you been running GFO?

Alk is slightly high if you are running essentially zero phosphates but your nitrates are 5 which seems OK.

Often times when first starting GFO or BP and you bring levels down really quick corals will RTN

[MisterP]

Nipping angels can't be overlooked but its hard to definitively say.

Try moving it to a temp holding tank and see what happens.

[johnandmar]

Had a flame angel that kept my Duncan colony closed for roughly 2 months....took a while to figure out the problem, but finally caught it in the act nipping away! Needless to say he's gone!

[silent_circle]

I just acquired an acre frag and I have Diy leds. Mine is losing color and partially turning white. I suspect it might be my lights. Not sure of not enough light or too much light.

[perikaruppan]

My fishes count is much lower than what my tank can accomodate
3 yellow tangs, one regal tang, one powder blue, 7 chromis, 4 anthias, 1 copper band and two Flame angels.
My feed regime is four cubes of frozen food twice a day.

I run a ATS to control my bubble algae which i had a major bloom - my friends called it Grapes farm !!!!

GFO has been running in my tank for over two years now, its not newly introduced, but i havent changed the media for the last few months.

[MisterP]

Well it seems you have a decent fish load for that size tank and feed pretty well.

Nitrates at 5 is OK and I wouldn't see that alone causing RTN.

Phosphates are low but you have a decent bioload so I wouldn't think that alone would cause RTN but the GFO still may need investigation if it hasn' t been changed in a while.

Have you had any recent large deviations in alk? Say a spike higher than normal or a drop then rapid correction.

Flame could be nipping and has aggravated them.

What water do you top off with and does it have any pollutants such as heavy metals that you could test for?

What is the salinity of the tank?

How long has the CBB been in the tank?

[jda]

Do you have another light that you can try, just to be certain? Everything else looks OK on the surface.

I don't see any AEFW bites on them, so that is good. What about red bugs? Any signs?

I have had plenty of picking angelfish and they don't kill coral, but they can irritate it quite a bit.

[perikaruppan]

Misterp:
I increased my alk over a period of few days from 7.2 to 9.6 to see if growth can be better.
Salinity is 1.025
CBB has been in my tank for about three months. he completely eradicated my entire aptasia problem.
I buy DI water from a supplier here and I use that for top up. Been using for two years now. I tried using poly filter also no change in color to indicate metals.

Suddenly I thought of some worm eucinid may be? That can eat the corals

Planning to investigate that tonight using red light.

[perikaruppan]

I have two 400w MH, three DIY led panels and te DIY cannon using AC-RC chip.