I feel horrible...

[turnblom79]

Last night I did around a 50% water change and added the dechlorinating chemicals immediately. Well within a couple of hours, half of my fish were dead and I feel horrible. I want to gradually restock and replace the ones that have died, but how do I prevent this problem in the future? I normally do about a 1/3 water change every other week and I have never had any problems. I have a 29g tank. Thanks for the help!

 

[GIS Guy]

If using the bucket method, premix the chemicals.
Make sure the temps are the same.

 

[MrBungle]

arrg GIS Guy beat me to it

 

[GIS Guy]

*DRUMMER* *SUNSMILE*

 

[FroggyFox]

how often do you do water changes? Generally doing a big water change isn't going to kill your fish unless (like the others said) your temp is way off or you have really bad water that needs to be mixed ahead of time. If you're using a python the best thing to do is put the declor in the tank and then add the new water.

IF you hadnt' done a water change in a very long time then its possible that you had fish deaths because of drastic changes in pH or nitrites/nitrates etc.

Overall if you have the technique down correctly with temp and declor, then the best thing you can do is more changes, more often. So instead of a 50% once a month try a 30% 3x a month or something along those lines. Best option would be 25-35% once a week.

 

[Dr.Gonzo]

It was most likely the temp of the water. Make sure it is as close to the tank temp as possible so you don't shock the fish next time.

 

[Dennis-Pir]

If as everyone says it is water, you can do smaller water changes more often so that the water temperature doesn't change as much.

 

[tropicalfish]

no, its not the water temp.
I have a ten gallon hex,.. I do water changes sometimes almost down to halfway of the tank. also, sometimes I forget to heat the water. The thing is, I just take a cup and scoop water in rather than pouring the whole thing in or pumping water in directly.

My bet is on treating the water AFTER it goes into the tank.