I think it's great ! Have some regenerated 4x's and just as good as day one .
Follow the instructions and it's safe :
https://www.seachem.com/purigen.phpAlso the "MSDS" :
https://www.dropbox.com/sh/iu6wapszkkos ... 151230.pdfI use a very little on some neighbors tank's along with a UV sterilizer that have big problems // result are amazing !
When I start I ask them for two white coffee cups. Fill one with there tank water and the other with tap water. There water is nasty color from the tank.
A week after I teach them a better way to maintenance there tank // same two white coffee cups /// fill with tank water and tap water again. Both still super crystal clear and clean ! I can only teach them , then it's up to them to just do it ! A few offer me money to do all there maintenance but I'm old and rather offer information than start a business. It's up to them to maintain their system once taught.