Sudden death

[dalston]

When I woke up this morning I found both my fish dead, they were happy and eating yesterday with no signs of stress or illness. All corals and inverts are fine. It is a 12 gal nano DX and has been setup +3 years but until 2 months ago was coral only. The 2 fish lost were a tailspot blenny and a small 6 line. I checked the heater for cracks and also the return pump and nothing is wrong with those.

Params are as follows.

Gravity 1.025 (tested with refractomter)
Ammonia - 0 (salifert)
Nitrites - 0 (salifert)
Nitrate - 2.5 ppm (salifert)
PH - 8.3 (salifert?
Temp - 81 to 82.5 over 24 hours
Flow - MJ 900 (in a 12 gal)
The only thing I have changed this month is the bulbs. No new corals or rock added in a while.

I was thinking maybe the oxygen levels may have killed them as the water surface was not being agitated too much, but why would this happen after 2 months?

Any suggestions or other aspects I need to check?

 

[Carlton'sTank]

I have no clue. Sounds very very strange. I figured I would give your thread a bump to see if someone has any helpful info.

 

[tmz]

I would guess that somehow O2 depleted. Perhaps a bacterial bloom. Was there any sign of cloudiness in the water?

 

[davewbush]

It could be to much water flow at night. When the fish tied to rest they were beat up against the rocks. I had this problem with my nano cube in the past.

 

[medic 125]

How does your coral look?

 

[FavaBean]

I was wondering how the corals are looking also....

 

[dalston]

TMZ, no cloudiness at all but I do run chemipure in the back chamber. O2 depletion would be my only guess too but what would cause this? I haven't changed anything or added anything for a couple months.

Davewbush, I'm not sure there is too much flow, I modded the return with a spraybar so the flow is very seperated and even in the tank. Both the fish had no trouble swimming and resting that I could see.

Medic and Favabean, corals look great I have complete PE on the cap, digi, and birdsnest, all zoa's and LPS are open and well too.

Thanks for the reply's