Water changes, pH swings and Co2 ... question.

[Ketso]

This is something that I have been wondering about for a few weeks now. I am running a DIY Co2 system that reduces my pH from 8 (ish) to 6.4 (ish). A difference of 1.6. Now, if I do a 50% water change, I am putting water with a pH of 8 back into the tank. Therefore raising the pH to around 7.2 in a matter of minutes.

Is this the correct line of thinking? And is it stressful to fish?:huh:

 

[Star_Rider]

you need to find out what the carbonate hardness is. CO2 if in the right amount will lower the pH(acidic reaction of CO2) but could also occur if your kH(carbonate hardness) is too low.

 

[Ketso]

This is the latest results of testing my tap water.
pH = 7.8
Amonia = 0ppm
Nitr>I<te = 0ppm
Nitr>A<te = 0ppm
Phosphates = 2ppm
kH = 2 dkH (35ppm)
gH = 8 dgH (143ppm)

And test results of tank before the water change. (no fish yet)
pH = 6.4
Amonia = 0.25ppm
NitrIte = 1.0ppm
NitrAte = 10ppm
kH = 5dkH 89.5ppm
gH = 12dgH 214.8ppm
Phosphates = 1.0ppm
Co2 = 60ppm

DeMonZ

 

[echoofformless]

There's no need to do a water change that large unless it's for some manner of treatment or specific purpose. Just a normal maintenance should be around 15-25% every week or every other week.