water change effect on ph

[john b.]

I noticed when I did my weekly waterchange on Sunday, that my ph does not change very much at all.The ph from the tap is 7.5 and my tank ph is normally kept at 6.3 or so. I did a large w/c (70%), and the ph went to about 6.5. My ph probe gave me the same result as my test kit.I would think that with such a large water change, the ph would have moved more then this. Can anyone offer any reasoning as to why the ph stayed realtively stable? Thanks,
John

 

[Tom Barr]

Re: water change effect on ph

Bacteria, organic carbon namely.

Try this, do a series of large water changes.
Also, try this on a new tank, say 1 month old.

After several months, most tanks are highly resistent to pH change.
This is due to the substrate.

It cannot be due to the water, you just removed it

Most aquatic substrates buffer to neutral.

Regards.
Tom Barr