• Seachem SeaGel is a premium aquarium filter media designed for marine and reef aquaria, blending MatrixCarbon and PhosGuard to remove organic color, phosphate, silicate, and toxic metals, as described by Seachem Laboratories.
• It provides enhanced water purification, lasting 3–4 months, and comes in bead form for optimal flow. 

Key Details and Usage

• Composition: A mixture of MatrixCarbon (for organic/color removal) and PhosGuard (for phosphate/silicate removal)
• Usage: Ideal for reef/marine tanks; can be used in non-phosphate-buffered freshwater, notes Seachem Laboratories.
• Application: Place in a filter bag; rinse before use, according to Aquaristic Online.
• Dosage: Use 500 mL for 300–450 L (approx. 75–120 gallons), explains Aquaristic Online.
• Warning: The product will release heat and fizz upon initial wetting, warns Seachem Laboratories. 
• Note: There is also a completely different product called SEAgel, which is a low-density, agar-based foam used in scientific research. 
• Seachem - SeaGel
• Although MatrixCarbon™ has the lowest detectable leachable phosphate content of all major carbon brands tested, some phosphate is still released. Adding PhosGuard™ to the mix compensates for this.
• Both components are bead shaped for optimum water flow characteristics and penetration.
• The components enhance each other and are ideal for reef and marine use.