pot scrubbers?

I was at a large swap meet today and came across a person selling all kinds of $1.00 items. Among them were packages of plastic pot scrubbers - six for a dollar. I bought six packs.
 
So I went out and got my new tank today along with a XP3 filter. The sales guy tried to convince me to buy some fancy Bio-media which I turned down. I said I was going with pot scrubbers as I read on this forum and he gave me the O_O face. Anyway how tightly am I supposed to stuff the filter with the pot scrubbers? As many as I can or simply comfortably fit them in? Also what is the life span on these things?

Thanks
 
I only put 4 in mine, that seemed to fit nice in one level of one basket in the XP3. But I'm also using other media, so you could easily put 8 in one basket I believe....depending on the size of the scrubbers you purchased.
 
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