EI co2 and fish health

Henry,

With lower light intensities, there's less need to approach such a fine edge.
Good high rates of circulation and O2 are factors also, and allow a wider range of CO2 to added without ill effects on fish or behavior.
I've bred Angels consistently, at 40ppm of CO2, Discus, Cories, maybe a few fish I'm not even aware of.

If they are breeding, they have good behavior, that's fairly safe to say.

How you approach the addition and adjustment of CO2 varies greatly person to person. Some are rather quick and rash, some assume you just add it and that's all there is to it. Some are scared, adding barely enough and adjusting it only a little.

Some change their tanks and the water level which drives off more CO2, some raise the water level or the biomass reduces flow which conserves CO2.
Evaporation can cause a lot of that.

Fish species seems to play a little role also.
Certain species of Plecos are more sensitive than most other species I've kept.
Tetras are tough as nails. Still, these things all play roles, so less light, better mixing and consistency for plant biomass, water level etc will aid in the reduction of the BBA etc, some use Excel instead.
Some go non CO2.

There are ways to make it easier to hit without stressing fish and reducing their stress levels.

If you feel strongly about this, you will want to crusade strongly against using pH controllers, CO2 24/7 etc.........ask folks to use lower light, more current etc.

You'll notice I do as a matter of philosophy
As well as non CO2 gas methods as well.



Regards,
Tom Barr