If you know you have an internal parasite you're not going to get rid of it w/ simple methods. The typical process is that you medicate the tank, the parasites are expelled and hang out in the substrate and then are re-ingested such that the cycle starts over. Some will say you should repetitively gravel vac the tank but that's too much effort and you're never certain you can say 'that's good enough'.
I take everything out of the tank. Decorations, plants, gravel, all of it. Add a serious UV sterilizer into the secondary side of your filtration and Chernobyl those little devils with a trip or two through my sterilizer. Once that's done I clean whatever else had been in the tank, spritz out the filter and start fresh. I live in cold country so for six months out of the year I can just move it out on the back deck and parasite survival rate has been zero at 0*f. Works like a charm. Just say no to parasites.