First time DWC grow, resevior strangely stinky

I just set up my single bucket DWC unit about 2 days ago, I filled it up with water and turned it on and now I noticed 2 days after that its starting to smell like something has gone rotten. I also added some nutes to it that are GH, not made for hydro but can be used with it says right on the bottle. Could it have gone rotten or something? because nothing is even growing in it yet I was just testing it. any tips?

what's your water temp? did you clean your bucket real good before adding in water and nutes?