I've been using Purigen for almost 5 years straight - 24/7 - in my discus tanks and another community tank. In one of my discus tanks I run 2 AC HOB 110 filters, both with Purigen, and which I alternate re-generating. I've found you can re-generate up to 15 times without the Purigen losing much of it's effectiveness, so it's very economical.
And you don't need to use any buffer - Seachem currently agrees with that, and in fact I believe they have recently removed the reference to buffering from their product directions.
Purigen is great, but ime it's best not to leave it too long before re-charging - do so as soon as it gets light brown - not brown or almost black - that way it readily retains & optimizes it's adsorption capability.
My tanks are crystal clear 100% of the time with the use of Purigen, among other clarifying/purifying aids.