I've been raising angels for almost 3 years and my MTS has got me up to about 1200 gallons of angels!
Sounds like ammonia and nitrite to me. However, this is especially true if your pH is well above 7. Ammonia is nearly non-toxic at a pH of 5, but very toxic at 8. I use Acid Buffer on my tanks and system to keep the pH below 7, mostly in case of an ammonia spike. I've never noticed any problem with lowering the pH suddenly causing angels to die...unless maybe if they eat a particle of the Acid Buffer. The nitrite spiking would cause heavy breathing since it binds to the hemoglobin in their blood. Angels will tolerate pH down to about 3.5 for a short time, but below 4.0 and they will stop eating after a while. I have a pinpoint meter so I'm always watching pH.
I lost a 29 gal tank full of dime size angels over a period of a few days because I replaced the HOB filter and figured the sponge filter in the tank was plenty. Then I got a little full of myself and didn't test ammonia for a couple days. By the time reality sunk in, they were all dead.
Massive water changes are only really OK if you can age the water and let the gasses come out. This is especially true in the winter if your tap water gets down around 40 degrees like mine does. If I let my water sit in a 500 gal container for 3 days then I can do a 100% water change with no stress even though the temp and pH are bound to be different. If you use tap water and do 100% and everything in the tanks gets covered in gas bubbles, then their fins get that, too. They don't like it.
Best thing in this situation is to have an ammonia and nitrite kit. If you confirm ammonia, you can lower the pH to 6.5 or so, put 1 tablespoon of salt per 5 gallons (to offset nitrite poisoning), and aerate the living heck out of the tank, then cross your fingers.
Sorry to hear your fish died. I know that's a bummer.
Sounds like ammonia and nitrite to me. However, this is especially true if your pH is well above 7. Ammonia is nearly non-toxic at a pH of 5, but very toxic at 8. I use Acid Buffer on my tanks and system to keep the pH below 7, mostly in case of an ammonia spike. I've never noticed any problem with lowering the pH suddenly causing angels to die...unless maybe if they eat a particle of the Acid Buffer. The nitrite spiking would cause heavy breathing since it binds to the hemoglobin in their blood. Angels will tolerate pH down to about 3.5 for a short time, but below 4.0 and they will stop eating after a while. I have a pinpoint meter so I'm always watching pH.
I lost a 29 gal tank full of dime size angels over a period of a few days because I replaced the HOB filter and figured the sponge filter in the tank was plenty. Then I got a little full of myself and didn't test ammonia for a couple days. By the time reality sunk in, they were all dead.
Massive water changes are only really OK if you can age the water and let the gasses come out. This is especially true in the winter if your tap water gets down around 40 degrees like mine does. If I let my water sit in a 500 gal container for 3 days then I can do a 100% water change with no stress even though the temp and pH are bound to be different. If you use tap water and do 100% and everything in the tanks gets covered in gas bubbles, then their fins get that, too. They don't like it.
Best thing in this situation is to have an ammonia and nitrite kit. If you confirm ammonia, you can lower the pH to 6.5 or so, put 1 tablespoon of salt per 5 gallons (to offset nitrite poisoning), and aerate the living heck out of the tank, then cross your fingers.
Sorry to hear your fish died. I know that's a bummer.
