small worm-like creatures in bubbleponic setup

hey guys,

this is my first setup and i'm having a few problems keeping insects and worms away from my plant.

i'm using bubbleponics for a single plant in an enclosure.

its week for me from germination. i noticed today that there where small worm-like creatures in my water, yhe water was all slimy as well. changed the water straight away.

i had a caterpillar on my plant about a week ago, i had to remove about 20-30 small black eggs with the caterpillar.

my main concern is the worms in the water.

are they harmful?
how do i get rid of them?
how are they getting into my water? (a bucket with a lid where the plant sits in)
does the caterpillar have anything to do with it?

my ph levels have been adjusted, the plant looks healthy ( except where the caterpillar had a feed ), temp is ok, water has co2 from airpump with air stone, slight breeze with a fan.

any ideas tips or hints would be great.

Pictures would be helpfull.

I would say water change the whole system. And flush the plants.
Keep the water temp above 70F.