🌀 Unicel C-8399 Replacement Filter Cartridge for Caldera Spas – 100 Sq. Ft. Part #C-8399 | 8" Diameter x 16-1/2" Length | Semi-Circle Handle | 3-5/8" Open Bottom The Unicel C-8399 is a premium replacement filter cartridge engineered for select Caldera Spas and hot tubs. With its high-quality pleated media and precise fit, this filter ensures efficient water filtration, helping keep your spa water clean, clear, and inviting. ✅ Product Features: 🔹 100 Square Feet of Filtration Surface – Large area for superior water clarity and extended time between cleanings 🔹 Durable, High-Performance Media – Made from heavy-duty Reemay® spunbond polyester for long-lasting filtration 🔹 Precise Fit for Caldera Spas – Designed for seamless compatibility with many Caldera models (see compatibility below) 🔹 Easy-to-Use End Caps – Semi-circle handle for quick removal and installation, 3-5/8" open bottom for secure fit 📐 Specifications: • Diameter: 8" • Length: 16-1/2" • Top: Semi-circle handle • Bottom: 3-5/8" open • Filtration Area: 100 sq. ft. • Material: Reemay® polyester 🔄 Compatible Caldera Spa Models (partial list): • Caldera Utopia Series (select models) • Caldera Paradise Series (select models) • Please verify fitment with your spa owner’s manual or existing filter dimensions 🔁 Replaces or is compatible with: • Caldera 73531, Pleatco PCD100, Filbur FC-3960, and other equivalent 100 sq. ft. cartridges 🧼 Maintenance Tips: • Rinse with hose every 2-4 weeks • Deep clean with filter cleaner every 2-3 months • Replace annually (or as needed for optimal performance) 🛠️ Premier Pool & Spa stocks a full range of Unicel filters for all major spa brands. Not sure if this is your model? Contact us for expert fitment help!