My new sump will have 3 filter socks, does anyone know a place to order a bunch of them, as I will need to have several sets on hand.

Thanks

I'd just make them myself. I can buy two yards of felt from Hobby Hobby and make about a dozen or so socks (4" diameter) for the cost of buying one or two commercial socks, depending on the brand. The trick will be findiing someone with a sewing machine that can do the seams (I can't recall what seam is typically used, but I'll see if I can get a pic of mine later today if needed).
If you are set on buying them, I'd order them from bulkreef supply. They sell theirs for like $6 each. Marine depot sells their 4" socks for $5 each.

Not a bad idea about making them. I have to ask the mother-in-law to see if she can do it, as she has a sewing machine.

Jehmco sells socks and filter material cheap.

black panty hose

What about knee highs? I use them to cover my filter intakes.

will the water flow through felt?

If you can sew or know someone who can, DIY is best

youtube.com/watch?v=JxEYMmnA4fE

That's what a majority of the socks are made of. I used felt from a hobby store for years with no issues.

+1.

Thanks all for the info, for now I ordered some in bulk from mcmaster dot com, so we will see how those work out

Sewing with a sewing machine is fairly easy.

If you don't know how, poke around at the local community college and see if they have any courses, check with libraries, or ask at a sewing/craft store about classes.

If none of those are an option, see if you can get a friend/relative who knows how to teach you a bit, or get an intro book out of the library and just practice and teach yourself.

Something like a filter sock should be really easy, and you may be able to figure out how after playing with some scraps and stuff