Waterchange?

[plantbrain]

I think the old advice stems from folks doing say once a a month or two water changes.
The pH drops and the bcarb/KH/Gh is all gone by then.

Then you add lots of hard tap water=> sick fish.

Much like dosing lots of bakign soda all at once.

CO2 does not have this effect, it's not a salt.

Regards,
Tom Barr