How do I know how much nitrous is left in the bottle?

[russeleo]

The most reliable method is to weigh the bottle to determine how many pounds remain. When a bottle is near empty (about 20% or less nitrous remaining) a surging effect is normally felt.

[milrivels]

The most reliable method is to weigh the bottle to determine how many pounds remain. When a bottle is near empty (about 20% or less nitrous remaining) a surging effect is normally felt.

The most reliable way is to weigh the tank. The minimum amount of nitrogen that ensures the performance of the system is about 20%.