Anyone use air conditioner foam filter?

[Uncle Dirty]

Here I am wondering again: does anyone use the air conditioner foam filter in their HOB filters? Wondering if it's safe to use in aquariums. Thought of using it with my BIO3 cartridges that I bought. I got 24 filters but only 1 blue foam piece.

 

[Uncle Dirty]

I saw them at my hardware store for $1.99 for 2 pieces about 16" x 24" and thought they would work in my whispers as bio filters.