I'm curious about using both chemi-pure and purigen as I have read some reviews where people are using both. Is it redundant or do they actually compliment one another?
Here is another thing I have always wondered about for years.

If activated carbon should be changed every 4-8 weeks and if left too long can leach contaminants back into the water, why does chemi-pure say it can be used for 3 -6 months before changing when it is about 70% activated carbon and 6 months is quit a bit more than the recommended life of activated carbon. Makes me wonder if it actually is safe to leave in place that long.
Any experiences/insight?
I'm asking relating to salt water tanks.