when i get a second hand tank i try to find out the background to it and ask why they dont have fish any more. For all you know there might have been something abrasive used in the tank before you got it so cleaning it thoroughly is a good idea. i use a tiny amount of bleach mixed with lots of water and then rinsed to death.
did you buy new gravel or was the gravel included?
what temperature is the water at and what do you have in the way of decor too.
did you buy new media for the filter or is that the old stuff you are using?
i would also say to use a dechlorinator that takes out any heavy metal as well.
do small changes with dechlorinated temp matched water for a few days and see if that helps any. the important thing is to keep an eye on the test results and make sure the ammonia and nitrite never go above 1.
if you followed the instructions on the bottle of dechlorinator and added it before the fish went in then there shouldnt be any chlorine in the water.
did you buy new gravel or was the gravel included?
what temperature is the water at and what do you have in the way of decor too.
did you buy new media for the filter or is that the old stuff you are using?
i would also say to use a dechlorinator that takes out any heavy metal as well.
do small changes with dechlorinated temp matched water for a few days and see if that helps any. the important thing is to keep an eye on the test results and make sure the ammonia and nitrite never go above 1.
if you followed the instructions on the bottle of dechlorinator and added it before the fish went in then there shouldnt be any chlorine in the water.
