Burnt leather coral death smell, help.

[therootcause]

My 24g nanocube has been set up since October 2019. Saturday morning I walked into the living room and was smacked in the face with an off smell similar to that of rotting coral and fish. My first thought was that the heater had cooked everyone overnight. To my surprise, all appeared well. I opened the canopy and the smell intensified. It smells like burnt rubber, heat (like if you leave a pan on the stove with nothing in it), and death. This is the first time it has ever smelled like anything other than saltwater. I noticed that the water level in the back of the tank where I keep floss, GFO, biomedia, chaeto, and sponge was low. I figured that part of the sponge had dried out causing the odor. I adjusted the height of the surface skimmmer which raised the water level, smell went away.

This morning I woke up and as soon as I stepped into the hallway I could smell it. Burnt leather coral death smell. This time the water level in the back was covering all of the media. Seeking suggestions at this point.

Parameters on Saturday morning:
Temp: 78F
Salinity: 1.026
Ammonia: 0-.25
Nitrite: 0
Nitrate: 40
Calcium: 440
dKh: 9.7

Here's what's in the tank:
Equipment: Skimmerless, chaeto refugium, gfo

Fish: 2 clowns and a starry blenny

Inverts: normal cleanup crew, skunk cleaner

Coral: long poly toadstools, white devils hand leather, plating sinularia, various mushrooms, plating and encrusting montis, small acros, leptoseris, pavona, pocillopora, birds nest, goniopora, hammer, photosynthetic sponge

 

[ahiggins]

Was your heater in the back and dried out? I’ve burnt up a heater or two that way and it smells like that.

 

[ahiggins]

Dead Corals/chaeto/live things don’t smell like death...they smell like fishy/ocean/ compost except intensified. Organic decomp smells very distinct. You couldn’t mistake it for anything other than dead coral.

 

[TriggerFinger]

Did your chaeto dry out? I got a shipment with some rotting red macro algae that had a terrible death smell...not burnt though. Could be a combination of dried out chaeto and burnt heater if both were dry too long?

 

[therootcause]

Was your heater in the back and dried out? I’ve burnt up a heater or two that way and it smells like that.

I have a 50w and 100w heater in the back, both of which are in the same chamber as the return pump. I wonder if one of them is touching the tubing or some plastic. I'll check this tonight. Both were still totally submerged on Saturday and this morning.

Did your chaeto dry out? I got a shipment with some rotting red macro algae that had a terrible death smell...not burnt though. Could be a combination of dried out chaeto and burnt heater if both were dry too long?

Ugh, I know that smell too. When I got my chaeto it had been in shipment for several days. Anything that was living (pods, etc) had died and started to decompose. I rinsed it with fresh water 5-6 times to clean it out before adding it to the tank. In this instance I don't think that it dried out at all. It's at the bototm of the "sump".