Opk question

Lauren • 29. Partner is 33. I work in a women`s refuge & he is a builder/roofer. We have 2 kids. Will 7 & Georgia - baby
How negative should an opk be when you're not building up to ovulation. And by how negative I mean, does a pink test line always show or when you're not building up to ovulation is it meant to be just the control line?