killing worms in small pond

Question
I have a small pond in my back yard. There are worms (or critters that look like worms) clogging the filter, and seem to be living on the bottom of the pond. How do I kill them? I don't want fish. I don't want plants. I just want the water. the pond is approx. 50 gals. I really don't care what kind of critters they are, I just want them gone. Is there something I can put in the water to kill them (and anything else that wants to grow).
As always
Linda

Answer
Even if you don't want anything living in there, animals will come and drink from the pond.  Therefore, I do not suggest adding poisons which kill everything.  If the worms are large and pink, they are probably earthworms which drown in the pond so adding chemicals wouldn't help anyway.  Normally, raising the pond edge above ground level prevents them from getting in there.  Most of the smaller "worms" are insect larvae and don't normally clog filters.  Some of them can be killed by Bt which is a bacteria that is sold as mosquito dunks or mosquito-killing liquid.  It also kills some insect larvae.  Also, most small animals are pretty sensitive to copper so if you added a copper-based algaecide, that would kill most small animals and algae.  It's not great for animals to drink but better than bleach.  It's a shame that you don't want life in there but with some routine maintenance, you can keep it as mostly just the water.

Robyn