water change calculation

[Bad Inferno]

I stumbled across an article on the web about water changes (cannot seem to be able to find it again). It showed that if you only changed your water like once a week @25% it was calculated that your fish are swimming in the equivalent of x months worth of unchanged water. They showed the calculations, it was not as simple as x% changed per month.

has anybody else seen such articles or know a web link.

[sharn]

ive seen something like that on simply discus http://www.simplydiscus.com/library/water_chemistry/general/wc_formula.shtml was that the one?

[Bad Inferno]

OH yeah that it 1000 thank you's

[fishgeek]

those calculatons are not taking filtration into consideration, just water change as only means for removal of pollutants

andrew