Corals not opening then melting. Found dead emerald crab in sump

[Nick762]

Corals closed for a couple of days then started melting today. Found an emerald crab that I put in the refugium to get rid of hair algae and it was dead decomposing. I did a 50% water change. Do you guys think it was an ammonia spike or something else and do you think the corals will recover?

 

[Nick762]

Im going to be honest - at least in that pic your tank looks fine. I mean the pic is a little grainy when i zoom in but it looks as though the gorgs polyps are out. Leathers and gorgs routinely shed. And a deceased crab in a 40g system would not cause an ammonia spike. At least it didnt in my 25g system.

Okay, I’ll keep checking the water for the next week and I’ll keep you guys updated

 

[Nick762]

How does the tank look now? Pic? Is this just your leather sloughing like they normally do for a few days? Was the crab dead or was it the molt?

The crab was dead and foul smelling when I took it out. I don’t have a pic atm as I’m not home but if you look at the thread. Those are the corals that seem to be the most affected by it. The zoas, gsp and frogspawn just have retracted polyps, no signs of melting.

 

[Nick762]

What is the flow like in your tank? I blast (relatively speaking) my gorgonians and it looks (in first pic) like yours is discolored on the inner stock. Which makes me think you need more flow

I have an 800gph powerhead running and the discoloration is the gorgonian melted towards the bony structure inside.

 

[EeyoreIsMySpiritAnimal]

I don't know the reason your corals are dying but I can say with 100% confidence that it's not from the crab dying. Ammonia is actually a food source for coral, so any "spike" that might have occurred from the decomposing crab would not harm the coral.
It's possible that whatever killed the crab also damaged your coral, but it will be difficult for us to diagnose that.

Did you make any changes recently, anything you added besides saltwater, and are your fish looking sick/stressed?

 

[Nick762]

I don't know the reason your corals are dying but I can say with 100% confidence that it's not from the crab dying. Ammonia is actually a food source for coral, so any "spike" that might have occurred from the decomposing crab would not harm the coral.
It's possible that whatever killed the crab also damaged your coral, but it will be difficult for us to diagnose that.

Did you make any changes recently, anything you added besides saltwater, and are your fish looking sick/stressed?

The only other thing I did was add some baking soda to the rodi water when I topped off the tank to increase my ph as it was quite low before at around 7.5 now it’s 8.3. Fish look fine don’t seem stressed at all. All are active and eating normally