lingering potion particles won't go a way!

I built a cool Minecraft village for U-Tube. I was throwing some lingering potions of harming2. Then I left it to do other Minecraft things. But when I went back to the village all the particles were still there. I tried going out of Minecraft and back in, even turning of and on my PC, but the particles are still there! Please help so I don't have to clone the hole thing to do U-tube.