I have 350 ml of Purigen 250ml in my Eheim 2073 and a 100 ML of it in my JBL external and I was wondering if its safe to recharge it with bleach as recommended?Because the beads are starting to go black and could do with being recharged but obliviously I dont not want to do it if its not safe.I would give a good soak in a strong mix dechlorinator after the 24 hours in bleach and try to make sure that all traces of bleach is removed but I still have that doubt in my mind that there would be a tiny amount of bleach left.