help needed pls

hi,i have read a few replies on nitrates,but im still having problems
my tank has been set up for many years@11
and i always do checks on problems but i introduced some new fish lately and now all my fish our dying, i have
2 mollies
2 guppies
2 gouramis
1 platy
my tank is also 4ft by 3ft not sure of how many gallons that is,but i checked my nitrate and its sky high over 80, i have done magor water change and even put nitro zorb in it and it still hasnt went down,i have checked ammonia,ph,nitrate and they are all perfect what happening,pls help

 

Can you clearify your post a little bit?

 

To understand a little better, you have your tank running for 11 yrs and never had a problem with NO3 until you added this new fish? If that is the case remember that everytime you add something new, your tank goes through a small cycle again. Or maybe your over feeding?

 

What are the NO3 and other levels of you replenishing water you do these water changes with ? You may be adding fuel to the fire, Unless you are keeping Discus or some other type of delicate fish then Nitrates in the 80's should not cause death just algae .

 

Do you use filter media? Do you clean and replace it often? Do you clean the filter out? Did this fish appear healthy when added?

 

Have you removed all dead bodies from the tank? Sounds like something is dead and its decomposing inside your tank.

 

i use a fluval 3 ihave cleaned it out and no i have had nitrate problems in the past but usually when i used nitro zorb it went down a little, my tap water has been checked and it was fine, i also use tap water safe in the water when i do a change, the tank is spotless an im only surmising that its the nitrate,like i said everything else is fine so i dont no what the cause could be...im t.xotally dumb founded by this,,ARRRRRRRHHHHHhh

 

Well by using tap water you could be poisoning them with some heavy metals ? OR unwanted poisons like arsenic to chlordanes. chlordanes are totally different then chlorines and some localities went to them and did not tell people about the switch my area sent out a notice for aquarium hoaquariest and lfs shops to make necessary precautions . Do you test water for ammonias , acids and what all ? What P.H do you maintian on average ?

 

my ph is sitting at a nice 7.0 7.5, i did treat the tap water before hand though..just lost another guppy

 

Do you have a ug filter in this tank? When was the last time you vacuumed the substrate?