After many months of (plain) distilled water I decided the build could use a little color. I went with purple and wasn't disappointed in the least. After a few drops the color was as shown. Each additional drop intensified the color giving it more "depth" I ended up using perhaps eight drops for a rather large loop and at that point you couldn't see through the reservoir and the tubing had a nice solidness of purple.
After several months I decided to disassemble the build and was concerned the various components would be stained. To my surprise the tubing, reservoir, CPU block, fittings and radiator all looked great and I couldn't even tell I had used the dye. Only the inside (copper) of the radiator had a hint of purple and a good flushing removed that.
When draining the loop I noticed the water wasn't staining anything it came in contact with which again I found surprising in a good way. All and all my hesitation about using the product over possible staining wasn't realized at all. And I just ordered Yellow for a new build...
