Worm-like creatures in drain tubes?!

3:06 pm in posts with pitcures!, questions, Seeking Advice by Dario Plehati

Hi to all! I was cleaning my tubes today from algae and found some nasty looking worms in drain tubes, and also many of them on the bottom of my pots. Here is a picture of one, mingling in tube:

  

Also, nutrient tank is clean, there where no sign of worms there, and airlift system also clean, just with casual algae.

Now i’m concerned about them, are they hazard to my health, and to plant’s health?

I taken whole system apart and rinse everything in boiling water to sterilize/kill everything. Three plants that i have left in system now where just flushed with tap water, and their pots where cleaned of worms also in hot water.

Is there any way i could find out from where did I get these creatures and how to get rid of them in future?