Angelfish Mysteriously Dying

Readings:
just taken>api Liquid test kit
[*]Ph 6.0 or lower
[*]Ammonia 0
[*]Nitrite 0
[*]Nitrate 0
[*]Phosphate 0
-> Partial was done Thursday (BEFORE they were added) @ about 20% and Partials are done regularly every week
-> Temp ranges from 77F to just under 79F
-> Prime is added everytime water is added
-> Plant additives are used (Seachem Liquid) per their dosing chart , but ignoring day 7...chart can be viewed here>>The Seachem Plant Dosing Chart
all other inhabitants are perfectly fine.
-> Filtration #1=Rena Filstar Xp4 with 30ppi foam, 20ppi foam, Eheim Cocoa Puff balls and ceramic Cylinders, and Micro-filtration pads
-> Filtration #2= AC110 with sponge and 1 bag of Bio Max
-> Filtration #3= Emperor 400 with Eheim Cocoa puff balls & 2 bags of purigen
-> UV Sterilizer=Coralife Turbo Twist 12x 36w ran 24/7 (bulb just replaced last month)
-> Lighting= 216w T5HO Ran 12 hours on timer (2-Giesemann 54W 6000K Midday Sun T5 HO Fluorescent & 2-Giesemann 54W Aqua Flora T5 HO Fluorescent) >>>Lunars come one automatically after bulbs shut off.
-> Air Disc comes on once regular Lights are off (for extra oxygenation) and shuts off BEFORE the regular lights return on.
This is a moderately planted Freshwater community tank with Eco-Complete Substrate


okay, just bought I believe a total of 8 angelfish the other day (Thursday) and all but 4 are dead and I haven't a clue why (other than low ph)?

they were all healthy looking specimens and slowly one by one have died.
The first one died within hours of being placed in the tank (seemed to have problems balancing)...so I kicked the flow to minimum on the ac110.

the next one I haven't a clue what happened to it (the whisker shrimp already had him to skeletal remains)....and after I found him I noticed another one was to skeletal remains (they had him hidden in the cave for later apparently).

The ones that followed were swimming happily one second...and laying "still" up and down the next (like instant death)!

The weird thing about it is that the short tailed ones were first to go (would have thought it would have been the longfin assuming they are more delicate).

Fish appeared to be healthy specimens with no signs of visible disease or problems...fish DO not have mouths open as when poor oxygenation is to blame and show no visible signs which I can think okay..this is what happened to you

 

The girl said she normally didn't work that dept and she didn't have a clue (I did ask, but forgot to test their water).
*regretting it now, big time*
And I acclimated them slow to be safe. Ugh!

 

You'd think that, but they shoulda showed signs basically instantly>>and only 1 died instantly (but again, it had problems balancing...so I think it might have suffered some sort of fin trauma when it was netted).
The rest looked perfectly fine...the remaining ones still do
*Confused*

 

1 remains>>busted the whisker shrimp with their bibs on hiding the "snacks" in the 1 white cave at the back of the tank.

That was one *Bleep* of a expensive dinner for them
<<Kicks self for buying them>>

 

i floated them in their bag for just under a hour (?35-40min) knowing they were delicate>>then I would remove a dixie cup of their water from the bag and replace it with a dixie cup of mine did that for about 30 min...all looked good>>netted and released into tank.

The first two that died I just tossed Stell.
then when the rest went the whiskers got to them before I could>>only skeletal remains...and I knew sure as cheeze whiz that Petco wouldn't reimburse for skeletons. I chalk this up to a very tough lesson>>buy the more delicate fish in LARGER size to reduce things like this from occuring.