I think I made my tank toxic. Why?

[bghill]

Last weekend I picked up a new 33gal to upgrade from the 25. I moved all the gravel and plants into the 33.
Filled the tank, brought it up to temperature, added a well used sponge over the intake of a new cannister filter and put in 5 neon tetras to do a soft cycle. (The original fish from the 25 went into my 15 gal for now). 1 neon died a few days later but the other 4 were fine. I was testing for ammoinia and was not detecting any so on Sunday (I week after set up and adding neons) I added about 5 small Black Skirts and everything went downhill from there. The next morning 2 black skirts and died and I was showing about .25 ammonia. I fished out the body's and added 2 capfuls of Prime AND moved over another sponge filter that had been on the 25 and kept running on the 15 gal.
1 hour later the tank was white cloudy, stinking of sulpher and the remaining fish were gasping at the surface and doing the staight up and down swim.
They all died before I could get them out and do a water change.
Where did I go wrong? I am suspecting it was the Prime due to the smell but not sure.

 

[The Zigman]

did you check anything other than the ammonia?
Nitrites Nitrates?

I thought Prime was a dechlorinator. does it remove ammonia?

 

[bghill]

I was just testing PH and ammonia? The ph dropped to around 6 or less from it's usual 6.6 - 6.8.

 

[austinpetemo]

my water has been cloudy ever since my last water change. dont know why never done it bfore

 

[The Zigman]

you should at least check the nitrite level in the tank..
NItrite is as toxic as ammonia.. if you were in mid cycle, your nitrites could have been high enough to kill them...

Not sure about the smell... you need a test kit, and a full water analysis, on your tank, and tap water.

 

[jpappy789]

nitrites are actually worse I believe.. could have been a spike without you noticing...

 

[247Plants]

Nitrates......the silent killer.

 

[bghill]

you should at least check the nitrite level in the tank..
NItrite is as toxic as ammonia.. if you were in mid cycle, your nitrites could have been high enough to kill them...

Not sure about the smell... you need a test kit, and a full water analysis, on your tank, and tap water.

I did not test for Nitrite's as I did not think they could build up that fast. 4 small neons on a 33 gal for 1 week I guess can do it!

 

[jm1212]

nitrite is worse than ammoina. it effects the whole body, not just the gills like ammoina does.

i think it was the pH drop that killed them. fish can usually withstand a change of .1 or .2 easily, but a drop from 6.8 to 6.0 will kill them.

 

[NickD]

I don't know if it's enough to kill the fish but 2 capfuls sounds like an awful lot for 33gal. Yes, Prime does smell of sulfur. But again, I don't know if that's enough Prime to cause the deaths.