I am making up a bunch of seed starter mix for next spring.

I got a good deal on big bags of perlite, however, the particle size is not sorted, it varies from almost powder to around 9MM. I use mostly peat pots that are small, abt 1.5 to 2 in. So when I make my seed starter mix (peat moss, perlite and vermiculite) I have to first screen the perlite. I checked a bag of Jiffy seed starter mix, and the perlite particles were not over about 5 MM. I am making up about 30 gallons of starter mix, so its too time-consuming to just pick out too-large perlite particles.

What I need is a piece of screen or a sieve with a 5MM mesh openings. I have searched the internet, and not found any screen of this specific size. I have found on eBay they are selling a three-piece soil seive set (high-dollar----abt $25.00!). One of the sieves is I believe a #10 mesh, but I don't have a clue what MM size it is.

I thought about using a piece of window screening, but the mesh size is really tiny, like under 1 MM.

Then the other problem is that once I have filtered out all the oversized particles, how can I crush them finer?