Take it outside and use the water hose. You want water pressure to clean it. Clean it inside and out. It will be a slight yellow. To get the rest of it out get hydrogen peroxide. If you get it stronger than 3% it will be better. Fill bucket with water & pour some hydrogen peroxide on the sock (inside out) it and just drop it in there over night. This will make your sock white again killing any organic matter left
You can see it here. It's a long post I made a few days ago and shows the sock being cleaned and a new one being added. I can use the same solution in the buckets for months.
Tank maintanance and how I do it