We measure liters per minute for HHO gas with a meter made especially for HHO gas (little pricey). I see a lot of people using meters in videos etc. that are made for air. This is not accurate HHO gas weighs differently.

Filling a liter bottle in a bucket of water leaves a lot of room for inaccuracy. I talk about this on 12 Things you should know about hydrogen conversion kitsit is number 3.

If your hydrogen generator is efficient and you are certain you are not creating steam, this is probably the best way to go without spending money on a HHO gas meter.

Take your HHO gas out hose while running your engine and let it feel up an empty liter bottle, while timing it with a stop watch and then doing a little math.

Thank You