Soaking in buo

[Armbags]

Hello cleaning gurus of MN
How long can I soak a cotton rug in bio washing powder and will it magically remove a decade of crusty old stains?
Anyone know how long you can soak before the bio damages the cotton? I am clearly clueless!
I've got as far as heaving the massive thing into the bath and scrubbing it all over with a brush to get the worst off but it still looks patchy, will soaking help?
DH tells me to bin it and get a new one but I would feel too guilty!

That was supposed to be bio in the title obviously. I think I've got it in my eye

As long as the rug is completely cotton; it won't be damaged at all. Only silk or wool can be damaged by biological detergents.
I've soaked items in a bucket for 2 days before now.
Soaking may well help, but depending on the stain and how long it has been there, it may not be completely removed.

Brilliant, thanks for your advice.
It's just general grubbiness rather than stains, although there are a couple of felt tip marks but I can flip it over luckily.
It seems to have come up well but it's hard to tell as it's still wet.
Thanks again!

You're welcome :)