I had this huge planter box made of wood in our middle bedroom, the plant finally died. So I moved the box outside and when I did, I saw that the carpet was stained where the box had been, I don’t think it is rust because there wasn’t any metal in the box, it might be from the water running through the potting soil and then getting on the carpet. Is there any hope of cleaning the stains on the carpet at that spot? Thanks.