Um...what?
Not sure what you're laughing about. Maybe you could actually, you know, say something that's helpful - like what's going on in your grow room, when the problem happened, etc.
If the tips of my clones were turning brown, I'd start checking out my pH to see if something was going on. I'd look at the room to see if things were too warm, if my plant hit the lights, were too dry, etc.
That's my troubleshooting advice. My other advice is to use a high quality nutrient, like Advanced Nutrients, to make sure you limit the problems you have, outside of human error. LOL