Sock will come off. Did you ever blow out the lines? While tank is down it would be a good to blow them out. Use a clean catch bucket so you can see what comes out. I did mine one time and was shocked at the amount of crap that came out.
If you remove tank sock You can keep your A/C pump and add a 30 micron prefilter to it. I make the special fittings for it just let me know if interested.