Parasite Proplem in pond
please HELP!! I have a parasite which looks like a pinworm, only is red in colour, and it destroys all water plants in a short period of time. It does not seem to harm fish, however, since all the plants rot very fast there is no shade to protect against algea, and fish lack oxygen. Water is murky and I have emptied this little pond several times, cleaned it out, but to no avail. the worms seem to behave like pinworms, and attack only water plants. They live in the water, cannot be destroyed, and were caused by one infected water lettuce that I bought and did not quarantine. the water lettuce looked white, but I didn't notice the problem until it was too late.
No one seems to be able to help, no water garden nursery seems to know what this horrible destructive parsite is. with my bad eyesight it looked like a cloud of dust in the water, where they swim around and multiply like pin worms. They hang on the bottom /roots of the water hyacinths, and when the plant is lifted up in the water, the fall off into the water like dust clouds. I thought it was a tiny bug, but upon close inspection it turns out to be a worm, mostly reddish in colour, 1/4 inch long and thin and coiling rapidly.
Can anybody help w/info about a cure? I am desperate.