Something's not right

[C.j]

2 days ago i bought 3 swordtails, and by today theyre all dead!

i decided to check water parameters to find out what might have caused this and this is what i got:

Ammonia: Negligable
Nitrite: Zilch
Nitrate: 20

not getting any clues from these i thought id try the other tests just to be sure:
Ph: 6.0 or lower!( test kit doesnt show anything past 6)
KH: had trouble getting this test to work (see below)
GH: 26!

with the KH test it said the test is finished when the colour went from blue to yellow, but it started orange and stayed that way. go figure.

im thinking maybe the ph shock killed em, not sure what ph the tanks are at the LFS but my bros tank in the same house as me has a ph of about 7.2, and his fish survived.


tankmates didnt seem to be the issue ( at least while i was watching them) coincidentaly i have 2 angel fish who have been surviving for ages in there, ive read that they like a lower ph while molly/ swordtails like a higher ph.

what do u think caused it? and how can i fix it?

cheers

EDIT: the tanks been up for about a year now

 

[Angry_Platy]

Your water parameters seem fine. Perhaps the swordies came from the LFS with a disease or problem. You might wanna go back and ask them how the other swords there are doing....

 

[dwarfgourami]

At the same time you can ask them what their ph is.

 

[WILDER]

I would find the ph to as that ph in your tank is to low for livebearers, and i can't see the lfs keeping them in that ph, sorry.