please help fish dying!

[lanabh]

hi guys haven't been on in a while but really in a panic with no where to turn my fish are dying off in the past ten days i've lost an angel a molly and short nose elephant fish! and tonight my blue acara is hanging at the top! they seem to hang at top for a week or so then just sink to bottom dead no other symptoms at all!
my ammonia, nitrate and nitrate are all 0
i do 10% weekly water change without fail i treat the water i replace with tap safe, as it has a high chlorine content, this is the only treatment in my tank
i have a 1000/lph external filter
temp is 26
its planted
trigon 350 l
internal filter for flow and extra filteration
air stone on 12 hrs a day
i feed tetra crisp, bloodworms odd dried tubifex cube, brine shrimp.
ph is high at 8 but it comes out of my tap at that
i have rummys with bright red faces and all fish are eating fine
other fish are mollies platies one angel 2 corys 6 glass cat fish, Columbia red tetras, upside down catfish i have added new fish in the past month without quarantine but dont add pet shop water
any help please as i will be fair pissed if i lose my acara

[Cermet]

First off - do a 90% water change.

Weekly 10% water changes are way too small - weekly water changes should be no less than 30% and 50% is better (of course, this depends on tank size; very large tanks don't need 50%.) Run air stone 24/7.

By the way, live worms, I feel, is asking for illness issues. I just don't trust those things - they are full of bacteria and parasites. Whether these harm the fish depends on a number of issues but I just can't justify the danger.

When did you last vacuum the substrate?

Something does not sound right - your nitrate is 0 and you have a well stocked aquarium with only 10% water changes per week? That does not sound possible unless you have an algae scrubber or nitrate removal filter. Are you certain the test kit is operating properly? Can you check it against a standard? or get another kit? Unless it is very heavily planted (is it?) and the plants are then suffering for nitrates, that number is very low.

[Cliff]

Perhaps you could get your test results verified by a LFS near you?

The 0 nitrate reading does seam a little odd to me.

[imma24]

How large is your tank and how long have those fish been in there?

Generally, when someone says their parameter readings are all 0, it indicates an uncycled tank - most tanks have SOME nitrates (20ppm or less)

Agree with Cermet that the airstone should be on all the time - fish always need oxygen! Also agree that 10% water changes are inadequate - most of us do about 50% weekly - even more often if you are losing fish.

[lanabh]

ok guys good spot there as checked water again and its 10ppm nitrate must have done something wrong not sure, but that still wouldn't explain whats going on? all the fish that died are new fish except the balloon molly who actuallynever looked right to be honest