Hi Don. Some people use it differently. I use it for about 10 days out of the month. This isn't always an exact number because sometimes I forget and leave it in there.
It helps clear up that 'yellowy' color and clears the water. It does take up trace elements, but with water changes, you will be fine.
I may experiment by just leaving it in there 24/7, but i haven't yet.
- Ilham