Way back in the day when Al.b.Fuct was around he told me never to use any metal components in a hydroponic system. According to Al, there is an ion exchange between the nutes and the metal. It effectively neutralizes your nutes...now I'm regurgitating what he told me from memory but its all in his threads.
A few years later, when I built a mini-fridge chiller using 50' copper coil, I found out he wasn't wrong. When my plants started to yellow out even though my EC was still were it should be. Within days, I lost the crop.
Now do all nutes react with metal...IDK? At the time I was using AN, and they reacted without a doubt.