I'll put in another vote for just using the 10ml (2 tsp) baking soda and 10ml citric acid (I actually bought dedicated measuring spoons after weighing the two different sachets they sell to see how much was in each: https://www.amazon.com/Adjustable-Measuring-Ingredients-Mete... )
If one wishes to set aside Sparkel saying "don't use generic" out of their financial interests, the counterargument I can see is that if one just uses a careless method for loading the baking soda and citric acid into the chute it actually is pretty easy to have it crystalize in the actual latch, or gunk up the rubber seal on the top-latch. I found that the $0.99 funnel from Ikea is the correct length to fit into their chute but under the top latch: https://www.ikea.com/us/en/p/uppfylld-funnel-bright-yellow-8... I'm, of course, positive there are hundreds of other funnels, but if you're already in Ikea, can't beat it.
As a frame of reference, I was in the kickstarter for the Sparkel, and thus this is the 3rd or 4th year of making my own charges with no ill effects. I've even recently upgraded to storing them in some of those lidded sampling cups so I can mix up 30 charges at a time versus having to get out the spoons for each bottle
If one wishes to set aside Sparkel saying "don't use generic" out of their financial interests, the counterargument I can see is that if one just uses a careless method for loading the baking soda and citric acid into the chute it actually is pretty easy to have it crystalize in the actual latch, or gunk up the rubber seal on the top-latch. I found that the $0.99 funnel from Ikea is the correct length to fit into their chute but under the top latch: https://www.ikea.com/us/en/p/uppfylld-funnel-bright-yellow-8... I'm, of course, positive there are hundreds of other funnels, but if you're already in Ikea, can't beat it.
As a frame of reference, I was in the kickstarter for the Sparkel, and thus this is the 3rd or 4th year of making my own charges with no ill effects. I've even recently upgraded to storing them in some of those lidded sampling cups so I can mix up 30 charges at a time versus having to get out the spoons for each bottle