Big ALS has 100 gram bags with purigen in it
Or a 250 gram bulk container which requires a bag
And By bag I mean "the bag" by Seachem (who makes purigen)
It has incredibly small opening in the mesh of the bag, due to purigen being very VERY tiny little balls
The bag 12$
250 grams of purigen 20$
100gram bags with purigen in it 12.99$
These are big ALS prices
But be patient
And Order it for less then half price on ebay/ amazon
I did find it helped
But nothing helped more then good filter floss and frequent (weekly) water changes with and everything cleaned with old tank water NOT TAP WATER
Yes I was lazy and cleaned floss and stuff with tap water, allowed to dry
And yes, killed my beneficial bacteria
I'd suggest at least 2 or 3 layers of floss in your stack of media
They even sell, If that doesn't work they sell (expensive) 50 or 100 micron floss , looks more like a thin fleece blanket
For example a human hair is about 170 microns (in diameter)
So 50 is VERY small
Good luck dude