Last year when I started my 46 bow tank, I bought plants from 3 different sources: thatpetplace.com, petsmart, and petco. I got java ferns, anubias, val and crypts. I rinsed them all off individually but did not dip any of them before placing them in my tank. About 2 weeks passed after the plants were in before I started seeing these thin 1/4 " to 1" long worms. At first I would only see one here and there, and my fish would eat them. I wasn't too worried about them until I started noticing them on the underside of my galss canopy top where they were laying clusters of tiny eggs. They were also right above the water level on the glass in the aquarium. They could be fully submerged in the water, but seemed to like moist, damp places better. They weren't harming my fish at all, so to say they're a parasite is probably incorrect. They look like microworms to me. They're a little thinner than fishing line and are white. Their bodies squiggle when they swim in the water. I will soon be emptying my 46 of fish and plants so that I can bleach everything in there to hopefully eradicate these worms. I know they're not harmful, but they're disgusting. I have set up a QT for plants I've been recently purchasing. I rinse the plants in warm water, then dip them in alum for 3 or 4 hrs. before putting them in QT. I really want to avoid plagueing the 46 or any future tanks with these worms or any undesirable inverts in the future (snails I don't mind). Is an alum dip sufficient? My newly purchased plants in the QT don't seem to have any worms, but maybe they didn't start out with any on them...
Free constant supply of food for your fish. If you have access to ghost shrimp, they will gladly rummage around the tank floor and eat those worms as well. 
