You should add 2-3 gallons of water now before the first regeneration because the instructions you have forget that your refill water volume will not be above the Air Check line on the brine pick up. Most of it will be below the line and unable to be used. That's because they didn't tell you to add water up to the height of the Air Check line on the brine pick up. So most of the Refill water will be below the Air Check line and not be able to be used. That means the first regen won't get the lbs of salt you want and all the 18K or what capacity you have used by the next regeneration won't be regenerated and you'll be running at a deficit from then on. Which can lead to hardness leakage.