Glycerin, Propylene glycol or fog machine liquid - what's best?

[Innotic]

Hello folks, it's me again.
I've successfully restored two of my lamps, but I want to make them even better.

Both are chinese products.
First one got problem with bubbly wax - not sure if it's problem with the liquid or wax? I've got many small bubbles which irrates me alot:
The other one is also chinese, but filled with Mathmos wax. Flows very nice (maybe too bubbly and less stretchy), but liquid is starting to cloud.

Now I want to make new liquids for this lamps without any salts. Which of these chemicals will be the best to use here? I need Your help, because i spend too much money on these babies already :)

[Red Letour]

I'm a bit new to this but can tell you that you need to let a lamp run for several days (3-5) before any trapped air or fluid bubbles get out of the wax. That changes the buoyancy (the specific gravity relative to the "water") of the wax and if you do anything before then, you'll only need to "fix the fix" afterwards.

I picked up a refractometer (specific gravity meter) for about $25 new on Amazon, and found my fluid was at about 1.3 using "original" old wax, with working results. I'm in the process of re-examining that and tweaking it, because getting the lamp to work PROPERLY is apparently way more subtle and complex. But any change you make, can require several days to "burn in" before you really know what it will do.