Change your res, clean it with mild bleach/water solution. Add fresh water and nutes. Then do maintenance from now on to keep it clean. Nut slime is no good, sounds like a personal problem Lol just kidding. But I started adding non scented bleach to my res every 3-4 days @ .7 ml per gallon. Problem solved and I don't use h2o2 anymore. Its been 6-7 weeks with no res change for me and everything looks good.
read that thread in the Hydro/DWC forum... its a sticky..
Make sure you have no light leaks into your reservoir and of course change it out before it effects roots.. if light is getting on the water your going to be breeding things you dont want like slime...