Water changes


Guru Class Expert
Aug 2, 2007
The information that I have gathered from this forum has been excellent and many thanks go to yourself and the other people that give such terrific advice.

I am now dosing using the EI method, but I have a query about doing the 50% - 70% water changes. It's very easy for me to do WC's as I am set up for it with aging barrels and pumps etc. What I need advce on though is that my tapwater is approximately a p.H of 8.1
When is the best time for me to do WC's? If I do WC's after the lights and CO2 have been running there is a big p.H swing as the new water goes in and the p.H goes up then there may not be enough time before lights out for the CO2 to bring the p.H down.


Prolific Poster
Sep 6, 2005
PH swings do to co2 will not affect the fish. Do your water changes at your convenience. Makes no difference. If your fish are like mine they will love the water changes. Mine gather right underneath the cooler water flowing out of my python.

Tom Barr

Staff member
Jan 23, 2005
Which is good news and makes your life easier.

It's a common question folks ask and one that's been resolved several ways: theory and in practical experiences(lots!).

So as Riverrat wisely, said, no need to worry about fish and CO2/pH issues, CO2 can kill if too high etc and if the O2 is also low etc (fish can gasp at the surface for at leasts two reasons, not just high CO2 alone).

Tom Barr