ophiura
Active Member
IMO, it is unlikely to tank the pH so low, so quickly, that it would be fatal. Low pH, in and of itself, is not really so much a fatal issue...IMO...I just don't see that happening, personally, that fast and that catastrophically. What do you keep your alkalinity at?
The only time I have seen a pH crash, that I can recall, is in a FO neglected tank that was old. A new large fish was added, and overnight the pH crashed (because alk was very low). The pH crashed because the addition of the CO2 overnight added enough acid without any buffering ability. This also often causes the tank to be quite cloudy due to interaction with calcium.
Was the tank "off" - without circulation - while this went on? How many fish died, what were they, and how fast did they die?
Did you add anything during this time? No new rock, just established rock? Is there any chance of a toxin (eg a kitchen sponge being used, soap/lotion on hands...and previous house cleaning during that time, including air fresheners). Fast inexplicable deaths like this are frequently narrowed down to ozone (note the case here), hydrogen sulfide, or some sort of toxin (eg fish - boxfish; sea cucumber; household product)
BTW, the fact that most inverts were unaffected is not surprising. It is quite common for inverts to be fine while fish are killed (eg organic toxins) or vice versa (copper).
The only time I have seen a pH crash, that I can recall, is in a FO neglected tank that was old. A new large fish was added, and overnight the pH crashed (because alk was very low). The pH crashed because the addition of the CO2 overnight added enough acid without any buffering ability. This also often causes the tank to be quite cloudy due to interaction with calcium.
Was the tank "off" - without circulation - while this went on? How many fish died, what were they, and how fast did they die?
Did you add anything during this time? No new rock, just established rock? Is there any chance of a toxin (eg a kitchen sponge being used, soap/lotion on hands...and previous house cleaning during that time, including air fresheners). Fast inexplicable deaths like this are frequently narrowed down to ozone (note the case here), hydrogen sulfide, or some sort of toxin (eg fish - boxfish; sea cucumber; household product)
BTW, the fact that most inverts were unaffected is not surprising. It is quite common for inverts to be fine while fish are killed (eg organic toxins) or vice versa (copper).