green stuff forming on my roots in homemade DWC will this be a problem?

I have some green stuff all over my roots in my homemade DWC, i washed it off with water but how do i stop this stuff and will it kill my baby plant. I am absolutely new to growing and just wanted to test out a hydro so i made a cheap DWC with an air pump and a 3 litre bottle small net pot etc. i put a cutting inside it and it sprouted roots in 14 days and started growing i was really happy. for the last 10 days i have been putting the little cutting under HPS and this green stuff started appearing, WHATS THE PROBLEM? AND MOST IMPORTANTLY WILL THIS GREEN STUFF KILL MY BABY PLANT ? SUFFOCATE THE ROOTS OR SOMIN? PLEASE HELP.
Also i do not have any cf/ec meter to measure nutrients and have a very simple cheap and crude PH tester which i use to keep the water nutrient about 6 but its very hard to judge simply by comparing colour. Nutrient wise i keep the nutrient solution very weak i am at 1/5 of the stated dose on the hydro nutes bottle. Does it really matter that i dont have the meters to read ph etc. basically i just wanna test out if the plant grows quicker bigger etc.

sounds algea coused by light getting into the rez.
do have a pic or 2 of your dwc set up.
algea will kill things in the end a slow death.

growem green-------------spike.

My god!! You say it will kill my baby!! Damn. I had a feeling it was light that was doing it, because it ahppened after i put under the hps. I will block light to the water solution. Thank you mate

I want to learn how to get rid of this stuff too.... NO I don't think it will kill your plants, but try putting a thick piece of cardboard under your hydro tray furthest from the drain. This will cause most of the water to drain after being watered instead of pooling and sitting there. Also change out your water if it is getting is the rez, I think it fux with pH more than anything plus it gunks up ur stuff.

Is there anything that can get rid of the algea w/o hurting the plant?