unclenedsfishfactory.com

low pH and other pH issues
--- Ned, March 2026

QUESTION: Why did my new fish spin out and die, the old ones are fine?
ANSWER: Please change your water often and stir the gravel first. Use dechlorinater.

The statement above tells you what time it is.
.....
The rest of the article below tells you how to make a clock, badly.

percentage hydrogen
indicates acidity or alkalinity
examples:
vinegar, coca-cola ... acid
pure water ... neutral
sea water ... alkaline

Normal desired aquarium range 6 - 8 depending on species.
Virtually all fish can tolerate pH 7, but its not ideal for all.
... the store's pH is usually 7.6 in the community tanks
and 8+ in the East African tanks (we add Seachem buffers).

Dangerous pH is below 4.5, particularly if the fish are not used to it.
... " used to it " is one of the biggest problems.

Aquariums that have been established for a long time, 1 - 6 years for example,
can slowly decrease water pH, particularly if deep gravel has not been cleaned
and/or water changes have not been done ...

but: those 6 year old fish grew up with that !
so .:. it has happened
more than once sadly,
that a customers fish are all fine,
then they added new ones that plummet to their deaths.

(I don't even put pH down out on the shelves, people don't realize the strength....
at 2 they can melt before your eyes ... eeeesh! ... the same thing your stomach does to food)

good idea to keep a test kit on hand
test both your tap water pH and tank water pH

basically
if you have a gallon of pH 8 water
and a gallon of pH 6 water
and mix them you'll get pH 7

It gets worse... sort of:
filter bacteria (which breaks down ammonia)
does not grow well in acid water (that's bad), but
the ammonia is not toxic in low pH water (that's good).

Here's the problem
you have low pH but high ammonia.
If you change half the water you will still have plenty of ammonia, but
it is now toxic because you raised the pH.
I would suggest changing all the water... cautiously.

pretty much
all that un-flushed goo gets yucky,
and you have to rinse it out

a little bit often is best