Our factory original replacement filters are designed specifically for Watkins Manufacturing makers of Hot Spring, Tiger River, Limelight, Hot Spot and Solana spas. The filters play a key part in Hot Springs’ “hydraulically balanced” systems. Hydraulically balanced means there is one square foot of filter fabric per one gallon of water flowing through their systems. This equation is doubled in the new patented Tri-X ceramic filters. Balanced water flow makes efficient filtering, perfect jet pressure and a happy jet pump.