plantbrain said:
I do not add a lot of peat. I've never had an issue with the CO2.
If you are using pure RO with 0 KH..............well there's much more reason to dissolve the CO3's out of the gravel.
Dissolution will greatly increase if the gradient is much larger.
See if the KH rises if you add KH 3 reconstituted water.
Good point, I'll have to try that, even though my scope is to have this tank run consistantly on 0-1KH. Hopefully the effect will taper off with time.
About CO2:
I do not pay much heed to keeping the CO2 at a certain set range based on pH/KH readings if things just don't look right in the tank.
That's pretty much the same for me too, I don't really test things much anymore unless I see a problem. But the poster was referring to the eco complete actually throwing off the KH/PH chart for measuring CO2 and I'm not sure that this is the case. I know peat can do this and many PH- buffers, I think you had posted a way to calculate that once...
... But with gases, the off gassing at night provides this prevention of build up of excesses. So no water changes are needed to achieve the same result on a daily basis with gases.
Amano does the same thing. Cranks the CO2 in there, then shuts it off at night.
Screw the "pH stability is better" idea. I've never found that to have merit and I've been doing this for over a decade with all these so called wimpy fish.
We've been here before

, I can't say I've ever killed a fish from CO2 either but I've always assumed that what 'everyone' was saying about the importance of PH stability to be true for fish. I'd love to see that myth broken personally, I'm just not game enough to try it in my tank

For sure the regular fluctuations that occur during large water changes have never hurt any of my fish...
I run CO2 24/7 now, have been for several months, I've found that even raising the rate of CO2 into the filter doesn't change much at all, my main tank likes to remain at 20-25ppm CO2 level and that's as high as it will go for me. Like I've suggested in the past, I feel gas exchange is the biggest consumer of CO2 and that is what is likely to be "regulating" this CO2 level in my tank. In my plant only tank, CO2 level has been fluctuating from 20-50ppm, plants don't seem to care, snails are still alive but no fish in there.
Regards
Giancarlo Podio