how large of a pressure tank do i need
In the past, pressure tanks were sized to store at least 1 or 2 gallons of water for every gallon per minute the pump can produce. A 10 GPM pump needed a pressure tank that holds 10 or 20 gallons. A 20 GPM pump needs a tank with 20 to 40 gallons of storage. Almost 2/3s or more of a tanks volume is filled with compressed air, it takes a very large tank to hold 10 to 40 gallons of water.