Can fish survive at ph of around 4?

[Avel1896]

When it comes to pH-meter it is better to focus on quality. Mine calculates pH, TDS, EC. I've had it for 11 years and never the slightest concern. It was worth €150 11 years ago.

 

[Lakshen99]

Maybe... How much CO2 (bubbles per minute) do you inject ?

about 1 bps or 1 per 2s in a 30l . I've been running this for quite a while now almost a year. Never did bother test for ph cuz i dont see any problems with the fishes. Fishes that are in rn are 1 betta, 1 cherry barb, 2 danios. Only reason why i bought the ph pen cuz it was cheap and i was curious to see what my ph is. Probably the readings of my aquarium are wrong as i do not think these fish will even be able to survive here.

 

[Avel1896]

about 1 bps or 1 per 2s in a 30l . I've been running this for quite a while now almost a year. Never did bother test for ph cuz i dont see any problems with the fishes. Fishes that are in rn are 1 betta, 1 cherry barb, 2 danios. Only reason why i bought the ph pen cuz it was cheap and i was curious to see what my ph is. Probably the readings of my aquarium are wrong as i do not think these fish will even be able to survive here.

Too much to me.
You should reduce to 30 bubbles per minute even 20 bpm. Do it very progressively.

 

[ArmchairAquariest]

Reduce the CO2 and add some carbonate hardness buffer so the pH sits a bit higher.

While most blackwater fishes from the Amazon can live in water with a pH of 4.0, they don't normally live in it all year round. When the wet season starts and the rivers fill up and flood the banks, the pH sits between 6.0 & 7.0.

^ I agree with Colin. Reduce the amount of CO2 you are putting in there, and add in a little calcium carbonate, that should bring the pH up a little and give you some buffering capacity. There is a bunch of ways you can do that: immediate adjustment would be various powdered thing and pills (including tums, but for small tanks do not use a whole one!) and a slow release can be achieved by just putting in some shells or a few limestone rocks or whatever.


Certain fish can live at pH4, but you may be really pushing the limit of what is healthy so raising the pH at least a tad would probably be a good idea.