Never seen them before, but was treated to a nice light show as I walked out of my front door on the way to the brewery to start carbonating a new beer I’m working on. One of the perks of having a business in the country. I like to start carbonating slow either at night or in the morning and let it slowly trickle in over a 12 to 24 hour period. Test it then hit with another 6-12 hours usually if it’s a little under. I bought an expensive tester once but I found that nothing is more accurate than just pulling a sample and testing with your mouth, a full pint at a time!