Urgent help needed with dying zoa colony

[johncarlo08]

Hi! Long time reader but first time poster. I have over 12 years experience keeping FOWLR and reef tanks and this tank is giving me the most issues out of any of them. This isn't my first time dealing with problems, this is just the first time i have never been able to remedy it without posting.

I need help with a colony of zoas that i have had for over 3 years that have been slowly dying over the last 6 months. I thought i was making improvements but after getting home from vacation this week, i can see the issue has spread to another colony of zoas on the opposite side of the tank (the 3 colonies between these two are unaffected). At first, my nitrates and phosphate were super high (see below) but after getting them under control about 4 months ago, the issue is still continuing. I use a turkey baster to clean off the affected coral colony about twice a week due to large amounts of detritus on it. I think the detritus is the dead zoa flesh because this isn't an issue on other colonies. I have watched the tank at all hours of the day looking for spiders or nudis and never found any. No zoa pox to speak of, plus i think i would have seen it on all the colonies sooner. I am truly stumped on what this issue is and am looking for help.

Tank info:
Nitrates: 22.5 ppm (this coral has experienced up to 40ppm without issue about 3 years ago)
Phosphates: 0.08ppm (this coral has experienced up to 0.60ppm without issue about 2 years ago)
Alk: 9.5 dKh (very stable around 9 for life of tank)
Calcium: 434ppm (very stable)
S.G.: 1.023 (very stable at 1.023 for life of tank)
pH: 7.9 (lower than i want but it has been this way since i started the tank, nothing not even buffer can raise this)
Temp: 78 F
Tank size: 70 gallon DT with 10 gallon sump. Sump has LR and DSB
Tank age: 4 years in august

Inhabitants:
2 clownfish
3 PJ Cardinals
1 Coral Beauty Angelfish
1 Watchman Gobi
1 6line wrasse
1 peppermint shrimp
1 coral banded shirmp
2 green tip anemones (split from 1 about 2 years ago)
snails and hermits (CAC)

Coral:
6 colonies of zoas (2 affected now)
1 red montipora

I have tried keeping hammer coral and frogspawn but they always bail out after several months. Fastest was 2 months, slowest i had for about a year before it too bailed out. I stopped getting coral 6 months ago when this started happening with my zoa.

Picture from July 2023

Picture from the start of June 2024

At the top of the picture you can see how the colony had spread to another rock, this has receded and that colony is now small and isolated from the rest.

 

[tedfisher496]

Have you done an ICP test?

 

[Gumbies R Us]

Have you made any recent changes to your tank? ICP test is not a bad option either.

 

[Mr. Mojo Rising]

What kind of light do you have and what setting? Corals hanging on and slowly dying after months often means inadequate lighting. Your parameters look fine for corals, so that leaves light and flow.

 

[william Lutman]

I bet parasite, do a dip. Save water change, add good dip, follow directions....

Looks to me like many polyps are there but irritated and closed.

 

[johncarlo08]

Have you done an ICP test?

I have not. I just googled it because i didn't know what that was. Do you have any personal recommendations? I found another thread in reef2reef talking about it and will likely go with one of those listed.

 

[johncarlo08]

I bet parasite, do a dip. Save water change, add good dip, follow directions....

Looks to me like many polyps are there but irritated and closed.

I have lots of brissle worms that live between the polyps. Any chance that's the source of the irritation? I ruled that out initially since i have them in all of my tanks and never saw an issue like this.

Any recommendations on what to use for a coral dip? I have never done one before but i know i can do RODI, H2O2, or one of the off the shelf chemicals.

 

[Solo McReefer]

Zoa Eating Nudibranch?

Turkey baster it at night with a flashlight?

How are your other zoas?

 

[johncarlo08]

What kind of light do you have and what setting? Corals hanging on and slowly dying after months often means inadequate lighting. Your parameters look fine for corals, so that leaves light and flow.

For light, i have 2 100W LEDs similar to this <link> set to either 60% or 80%.

For flow, i have the sump return nozzle, 2 1600 pgh wave makers on either end of the tank, and 1 90 gph pump at the surface to help push surface crap to the sump return.

 

[johncarlo08]

Zoa Eating Nudabranch?

Turkey baster it at night with a flashlight?

How are your other zoas?

I'll try the baster at night, so far i have only done it during the day. I can't rule out the nudi or spiders but i haven't found them after months of searching during the day and at night.

With the exception of the 1 zoa colony that just started doing the same thing, they are all fine i think? At least they are 100% open and not doing this.

 

[johncarlo08]

Have you made any recent changes to your tank? ICP test is not a bad option either.

No changes within the last 4ish months. Last thing i did was to add a GFO reactor to help drop the phosphate below the 0.10ppm threshold.

I also started to keep my tank lids off to see if the pH would go up but that hasn't had any affect on it. Still steady at 7.9 all day and night.

 

[Mr. Mojo Rising]

For light, i have 2 100W LEDs similar to this <link> set to either 60% or 80%.

For flow, i have the sump return nozzle, 2 1600 pgh wave makers on either end of the tank, and 1 90 gph pump at the surface to help push surface crap to the sump return.

They are good lights but that is a big tank. I would suggest to turn up the lights or rent a par meter. Corals get 90% of their energy from the light, this is the most important thing to be sure of.

 

[johncarlo08]

They are good lights but that is a big tank. I would suggest to turn up the lights or rent a par meter. Corals get 90% of their energy from the light, this is the most important thing to be sure of.

Okay, i'll bump it up to 100% on each light and report back within the next few days.

Since this just started a few months ago, is it possible that the lights are dying or going out of their specified wavelength since they are 4 years old? Thinking about it, all the other zoa colonies are under the 2nd light or between the two of them so maybe this one is going bad? Idk if that is a thing for LEDs

 

[DED65]

Turn your lights up slowly! Don’t try to raise them to 100% today. You can go 2-3% and give it a few days and repeat!

 

[DED65]

How long ago did you start with the GFO?

 

[johncarlo08]

How long ago did you start with the GFO?

4 months ago. I've only had to replace the media once in that time but i'll probably do it again soon because it's looking a little worn.

To answer your other question, unfortunately the light only does intervals of 100%, 80%, 60%, 40%, 20%, and 5%. They were at 80% so i bumped them both up to 100%

 

[Mr. Mojo Rising]

Okay, i'll bump it up to 100% on each light and report back within the next few days.

Since this just started a few months ago, is it possible that the lights are dying or going out of their specified wavelength since they are 4 years old? Thinking about it, all the other zoa colonies are under the 2nd light or between the two of them so maybe this one is going bad? Idk if that is a thing for LEDs

Was there any new livestock introduced in the past few months?

 

[DED65]

4 months ago. I've only had to replace the media once in that time but i'll probably do it again soon because it's looking a little worn.

To answer your other question, unfortunately the light only does intervals of 100%, 80%, 60%, 40%, 20%, and 5%. They were at 80% so i bumped them both up to 100%

Watch them close for any bleaching. I don’t believe it is the lighting, usually zoas will stretch for light if they need more. It looks like they are being irritated, do your shrimp ever try to pick food out of them?

 

[johncarlo08]

Was there any new livestock introduced in the past few months?

I added the wrasse a month ago because i got him in a raffle at the LFS but the problem was in full force before i added them

 

[johncarlo08]

Watch them close for any bleaching. I don’t believe it is the lighting, usually zoas will stretch for light if they need more. It looks like they are being irritated, do your shrimp ever try to pick food out of them?

Okay i will! I will also watch the Monti for signs of bleaching, i think it would show there first.

The shrimp definitely crawl all over the zoas but i've never seen them pick at them. They will do this with all of the zoa colonies tho, the healthy and unhealthy ones.