New Fish Keep dying

[bal009]

Guys,

I have a 29g biocube that has been running for a few months now , all parameters look fine (even took a sample water to my LFS to confirm results) but every time that i add new fish they start swimming weird( up-side down) and eventually die after a few days. One thing i would like to add is that i'm not sure if the heater installed in the back melted part of the plastic, i m just bringing this up because the only unusual thing i've noticed lately is that my poly-filter pad is turning black right after being replaced (see image attached), so i wonder if the water has any toxins since black color on poly-filter is not common.

Any help is greatly appreciated.

 

[Dale_M]

Check for electrical short.
Maybe your heater has malfunctioned and your tank is now electrified.

Check out this thread...
http://www.reefcentral.com/forums/showthread.php?t=2182599&highlight=stray+voltage

 

[DancingShark]

I would do several big water changes and run some carbon. Maybe something in the water the tested are not picking up or not being tested for. I would also just buy a new heater.

 

[Uncle99]

Electrical short is messing with their lateral line.
Remove this heater