Quote Originally Posted by chem geek View Post
You wouldn't replace it every couple of weeks unless you had a lot of metals in the water, the bag absorbed them (usually, but not always, coloring the bag), and you measured a drop in metal concentration but was still not low enough. Whoever described replacing it every couple of weeks was probably trying to make money from selling it, but even the manufacturer doesn't say to do that.
The mfg is saying every 30 days (4 weeks):
Discard used PowerPak after 30 days. (Note: PowerPak contents MAY change color.)
from
http://www.culator.com/eliminating-metals