Piezography colorant

I'm a big fan of Pieozgraphy but I have one issue... the low visibility of a nozzle check. It's a very dilute pink and hard to see. I'm thinking of adding about 5ml of magenta (not the light version) to about a 100ml of the Piezography in its present state. It might need more.

Is the present colorant dye or pigment? I want what I add to be the same.

Any other suggestions? I'm using Piezograph as a storage fluid right now, and I use it also for general cleaning.

Thanks all!