Cotton yarn for blanket stitch machine

[medion]

Hi all,

This is a bit off topic as it's not a leather machine per se (this is my only non-leather sewing machine), however I know there is a wealth of knowledge and industry here and I was hoping someone might have an answer.

Does anyone own a dedicated blanket stitch / crochet stitch machine - most commonly built by Merrow? I own one for whipping blanket edges. I currently use a 5/2 weight cotton yarn for this, however I am noticing the yarn I use often has knots in it, which is ripping through my needles. Has anyone worked with these machines and able to recommend what kind of yarn/brand/weight is commonly used in production blanket edge stitching?

Cheers! Medion