Cleaning Seachem Purigen

I have a bag of Purigen in my sump
https://www.amazon.co.uk/Seachem-Purigen-250ml-Laboratories-Inc/dp/B018OIUAK4/ref=sr_1_4?ie=UTF8&qid=1504113642&sr=8-4&keywords=seachem+purigen
It is claimed to reduce Nitrates so I took a chance on it and liked it because it can be 'regenerated' by soaking in ammonia - Incidentally I think it does have an effect in Nitrates because there appears to have been an increase in weekly Nitrate build up since I removed it to regen it.
Anyhoo, a few weeks ago it was regen time, I tried standard 9.5% ammonia (Cleenoff) mixed with water, no effect overnight, so I repeated, still nothing. Then I tried it neat and left it for a few days, by the time I checked it the ammonia had gassed off and still minimal effect, so I tried neat in a sealed container, nada. Not to be beaten I ordered 33% ammonia (WOW this powerful stuff, they say dont sniff the 9.5% stuff, dont breath near this even when outside) This finally started to have affect, but it has taken some time.
So all I have to do now is rinse and dechlorinate (yes I know its ammonia), and now we get to the reason for the post.
I rinsed the bag really well outside with a hose first (remember its powerful stuff) it killed all the worms that were hidden under the gravel, I tried to wash them off as soon as they came to the surface but it was too late Then I brought it in and ran it under the tap for a good long time before leaving it soaking in water for two days with a massive dose of API water conditioner. Rinsed again and left to soak for another day before testing the water for ammonia, it went off the scale. I have repeated this three times now and can still detect ammonia but just 0.7ppm last time.
I know the strength of the ammonia will have had a lot to do with this but beware the highly porous nature of the Purigen must retain ammonia, if anybody uses this media or anything else that can be cleaned with ammonia ..... test it, even when you are sure its completely clear.

@Sue Why use Ammonia? A good question indeed and maybe a lot to do with the poor results (I sense you are smiling as you read this) Then I have been an idiot? Worst than that, I told everybody! I always thought (without actually thinking) that bleach was a dilute ammonia solution Oops! Guess which section of the supermarket I'm off to in the morning.
Luckily no fish were harmed in the making of this cock-up