You're welcome! Purigen is a replacement for carbon. Most people avoid using carbon in planted tanks because it removes some of the fertilizers that we add to feed the plants.
If we use driftwood or some other decoration that makes the water yellow or brown and want the water to be clear, without stripping away our ferts, Purigen is the go-to chemical media. It's cheaper than carbon, does a killer job at making the water crystal clear, and last for years because it can be regenerated and used over and over.
A lot of people don't use any chemical media and their tanks are awesome. It's not necessary to use anything in a lot of tanks. If you happen to have yellow/brown water and want it to clear up Purigen is king. Carbon is still important to have around though, just in case you have to medicate a tank to fight a sickness. Carbon is the best at removing the meds after the treatment is finished.