Q ~ What makes 25% Lye mixture?

I recommend 25% lye to water by weight.  
I understand that may be a little confusing because people ask “Is that 250 grams for 1 liter or 250 grams for 750 CC?”
Actually it isn’t that critical and either will work.  I usually use the former and the latter is technically correct.
You don’t want too much lye or it will actually inhibit the electrolysis process.  It’s actually hard to have too little, as little as 5% will go a pretty good job.
Research shows that 25% is usually optimum but it takes considerably less before efficiency drops off significantly.
I like to start with the lye on the ‘upper’ end (densest mixture) when the electrolyte mixture in the HyZor is the lowest, because as you add water it will thin out the mixture.
Also, over time, there is a tiny loss of electrolyte out with the BG.  That’s why you MUST run the BG through a filter on the way to the engine… because if lye gets into your engine, it will corrode (eat) your engine’s aluminum components.