I have some, but haven't tried it out yet. I've read about it a bit though, and from what I remember... Yes, it can be used again. It works with enzymes. It can be reused over and over but will work more slowly each time. Eventually you'll need to get new. Store it in a sealed container because open air storage will make it less effective. Do Not pour the used portion back in with the new portion or the rust residue floating around in the used stuff will use up some of the enzymes in the new stuff, which would be wasteful.

Tav