Worms in my filter?

sounds like nematodes. most are scavengers which are introduced to the aquarium in egg or adult form. Eggs can be present in almost anything that you add to your aquarium; feeders, live plants, driftwood etc. Adult worms are more likely to be introduced by live plants and in the water accompanying your feeder fish.

since they feed on organic matter in the gravel (or filter in your case) populations of nematodes can be reduced or elimated by stopping overfeeding, thorough gravel vacuuming and increased water changes.

I had a similar problem in an overstocked tank. I performed heavy gravel vaccums and took out probablt 100+ worms. After doing so, I waited a week and then I started finding smaller ones (probably newly hatched ones).

By those days, I had to tranfer all the fish to a bigger tank, so when I was passiong gravel from one to the other, I boiled for 10 minutes and a lot more worms appeared (now dead).

Since then, my tank is worms free.

Do you plants go thru quaruntine or right into the tank? quite possibly worms from snails that came in on your plants. it'sfor this reason i farm my own snails for my larger tank. depending on the worm it might be difficult to kill off as some of those can build up quite the defensive barrier. can you provide a picture?

I have a population of tubifex in two of my tanks. They don't seem to overpopulate or cause problems, and I kind of like having them in the tank for biodiversity. They are also a great source of live food that require no maintenance, and I think they are beneficial to the plants much like earthworms in a garden.

I think in your case it does sound like nematodes as liv2padl suggested. I've never had those in my tanks as far as I know.