There are many products designed for filtration lines, check with your supplier. You need to treat, scrub and use an edging tool. The problems is even you are successful in getting the bulk of the staining out, it is going to come right back unless you correct the condition. I had good success with Prochems's filtration line product. I had a condo building that was brandnew, never lived in but had filtration lines everywhere due to the large gaps between the walls and carpeted areas, made worse because of the heat pumps installed in every unit to control heat and air conditioning. They needed the remove the lines so they could sell the suites. We charged a fortune, spent days on our hands and knees scrubbing, rinsed with pmf edging tool and wand. We improved it considerably but as people moved in the lines kept coming back, in some cases 8 inches wide. I still clean for some residents in the building and most have given up on that carpet (snow white) and have replaced it. Some of the residents who actually listened to what I had to say, have had the gap filled with expanding foam, before replacing the carpets. Some filtration is cleanable, some is a waste of time and money. These days, I just prespray the lines and edge with a full size edging pmf tool, if I see it is improving, I will keep at it. Otherwise, I don't want to spend a lot of time with it.