Century Lamp - want to change color of liquid

Hi, I'm new to this, so bear with me - I just acquired a second Century lamp (silver base) and the liquid is purple (looks red when lamp is on) and the lava is yellow or off-white. All the other lamps I own have blue liquid, and I was looking at all the formulas on the site and got a little confused.

Is it true that if I want merely to change the color of the liquid that all I really need to do is empty out the old liquid, use some distilled water and sea salt, plus perhaps a drop or two of dishwashing liquid, and I can color the water as I wish (like with food coloring)? Is this all it takes, or is that liquid formula only if I make my own lava?

Thanks...

--Cat > ^ . . ^ <