I run 11.74 oz of chemi-pure elite and 100 ml of purigen in my 20L sump for my 50 gallon DT. How often should I replace the chemi-pure elite and the purigen?:question:
I'm not sure about the chemi-pure, but purigen says to recharge it when it goes from white to brown. You recharge it by soaking it in bleach water. There were instructions on the box I got ages ago, so you might look for that.