di cartridge question

[maxima2k2]

i have a csp 160 gpd i notice the di cartridge is starting to change color from brown to green (about 1/3 of the cartridge is green) my di meter says it;s still ok to use when i push the button my question is that when do i change the di cartride when the whole catridge change color or when part of the cartridge change color
thanks

[SpectraPure]

Max,

All is well until the lighter color is 80% of the total height.
That last 20% does its job, but it goes quicker. Best to have
a new cart in hand at or around the 80% point.

Scott
SpectraPure, Inc.

[maxima2k2]

thanks