I got an older carboy from a friend that was real dirty. So i cleaned it with oxy clean, and it hazed up the glass really bad on the inside. I have never had this happen with my other carboys, is it ruined? Why would it do this?
If you used warm/hot water, it could be humidity inside doing it. Did you scrub with a carboy brush, sanitize, rinse with cold water, and let drain upside down?
It's probably oxyclean "scale"- a reaction to minerals in the water. Happens on bottles all the time, a soaking in a weak acid/water solution, like starsan and water, lemon juice and water, vinegar and water, or clr will clear it up.