Unicel Cartridge, 50 sq ft, 7CH-50

The Unicel 7CH-50 is a 50 square foot replacement filter cartridge, 7 inches in outside diameter and 14-3/4 inches long. Unicel lists it under Coleman Spas, DM Industries, Sunrise Spas of Canada and Wild Water Spa.

Matching the cartridge

Cartridges are matched on three things: outside diameter, overall length and the end caps. Get the first two from the numbers above and compare the ends against what you pull out. Ordering by the Unicel part number is the surest route when the original marking on the old cartridge has worn away, which happens quickly in a spa.

Cleaning and replacement

Regular rinsing gets a cartridge through a season, and a soak lifts oils and scale that a hose cannot. There is a limit: once the pleats stay discolored after cleaning, or they splay, mat together or tear, the media is spent and flow will not come back. At that point the pump is working against the filter, and a new cartridge is the cheaper answer.