🔷 AFM® NG 21kg Grade 3 – Premium Activated Support Layer Filter Media

🔷 The Essential Foundation Layer for Superior Pool Filtration Performance

📋 Product Overview

AFM® NG (Next Generation) Grade 3 is a precision-engineered support layer filter media manufactured by Dryden Aqua, the world’s leading specialist in activated glass filtration technology. This 21kg bag contains coarse-grade (2.0–4.0mm) activated filter media designed specifically to cover filter laterals and provide optimal flow distribution during both filtration and backwash cycles.

Unlike standard gravel or crushed glass alternatives, AFM® Grade 3 undergoes Dryden Aqua’s unique three-step activation process, creating a self-sterilising, bio-resistant surface that prevents bacterial colonisation. This ensures that even your support layer actively contributes to cleaner, healthier water rather than becoming a breeding ground for harmful microorganisms.

AFM® is the product of over 30 years of research and development by Dr. Howard T. Dryden, and has been independently verified by IFTS (French Institute for Filtration and Separation Technology) to double the performance of sand filters. Manufactured from 100% recycled green and brown glass bottles in dedicated facilities in Scotland and Switzerland, AFM® Grade 3 represents the gold standard in sustainable, high-performance pool filtration support media.

⭐ Key Features

✅ Self-Sterilising Surface – The unique three-step activation process creates a bio-resistant surface that generates free radicals, preventing bacterial growth and biofilm formation on the media

✅ Optimised Particle Size (2.0–4.0mm) – Precision-graded coarse particles designed specifically to cover filter laterals and ensure proper flow distribution

✅ Superior Hydraulic Performance – Controlled sphericity (0.81) and uniformity coefficient (1.4–1.8) maximise water flow whilst preventing channelling

✅ Guaranteed 10+ Year Lifespan – Dryden Aqua guarantees performance within 10% of new specification after 10 years when used correctly

✅ Essential DAISY® Component – Fully compatible with the Dryden Aqua Integrated System for complete ecological pool water treatment

✅ 100% Sustainable – Manufactured from recycled glass using 100% solar power and rainwater in a closed-loop production process

✅ Certified Safe – NSF/ANSI/CAN 61 & 372 certified for drinking water systems; UK DWI Regulation 31 approved; HACCP certified for food production

✅ No Sharp Edges – Unlike crushed glass, AFM® is processed to eliminate sharp edges that could damage filters or injure installers

🔧 Technical Specifications

Specification	Grade 3 Value	Standard
Product Type	AFM® NG Activated Filter Media	–
Grade	Grade 3 (Support Layer)	–
Particle Size	2.0 – 4.0 mm	ISO 13322-2
Effective Size (d10)	2.3 ± 0.3 mm	ISO 13322-2
Undersized Particles	≤ 10%	ISO 13322-2
Oversized Particles	≤ 10%	ISO 13322-2
Sphericity (Average)	0.81 ± 0.01	ISO 13322-2
Uniformity Coefficient (d60/d10)	1.4 – 1.8	ISO 13322-2
Roundness	0.65 – 0.68	ISO 13322-2
Hardness	5.5 – 7.0 Mohs	ASTM C-730
Uncompacted Bulk Density	1.43 kg/l	EN 12902:1999
Porosity (Uncompacted)	42 ± 2%	ASTM D-7263
Porosity (Compacted)	37 ± 2%	ASTM D-7263
Specific Gravity (Grain)	2.4 – 2.52 kg/l	GTS QP9
Attrition Rate	< 1% (50% bed expansion, 100h backwash)	–
Organic Contamination	< 50 g/mt	–
Coloured Glass Content	> 98% (green/brown)	–
Bag Weight	21 kg (46 lbs)	–
pH Tolerance	pH 4 to pH 10	–
Temperature Range	0°C to 100°C	–
Material	Activated Aluminosilicate (Recycled Glass)	–

📊 Grade Selection Guide

🎯 AFM® is available in multiple grades, each designed for a specific function within your filter. For optimal performance, multiple grades should be used in combination.

Grade	Particle Size	Type Available	Function
Grade 0	0.25 – 0.5 mm	AFM®s only	Extra fine filtration – 98% particle removal down to 1μm
Grade 1	0.4 – 0.8 mm	AFM®s and AFM®ng	Main filtration layer – 95% particle removal down to 1μm (ng) or 4μm (s)
Grade 2	0.7 – 2.0 mm	AFM®s and AFM®ng	Support and filtration layer – removes particles down to 5μm
Grade 3	2.0 – 4.0 mm	AFM®s only	Support layer – covers laterals for proper flow distribution
DIN	0.7 – 1.2 mm	AFM®s and AFM®ng	Special grade for high TSS loads and DIN-standard pools

Recommended Grade Combinations:

Standard Dual-Layer Configuration (Filters < 800mm bed depth):

• 60% AFM® Grade 1 (filtration)
• 40% AFM® Grade 2 (support/filtration)
• Grade 3 to cover laterals (if fitted)

Three-Layer Configuration (Filters > 800mm bed depth):

• 60% AFM® Grade 1 (filtration)
• 20% AFM® Grade 2 (support/filtration)
• 20% AFM® Grade 3 (support layer)

⚠️ Important: AFM® Grade 3 is specifically designed to cover filter laterals. Use filter manufacturer’s dimensions to calculate the required volume of Grade 3 needed to fill the space below and cover the laterals.

📐 Quantity Guide

🧮 AFM® has a lower bulk density than sand (1.43 kg/l vs approximately 1.55 kg/l for sand), so quantities by weight should be reduced by approximately 15% when replacing sand.

General Guidance:

The amount of AFM® Grade 3 required depends on your specific filter design:

• Filters with laterals: AFM® Grade 3 must fill the space below and cover the laterals completely
• Filters with nozzle plates: Grade 3 is typically not required

Calculating Your Requirements:

1. Consult your filter manufacturer’s documentation for internal dimensions
2. Calculate the volume needed to cover the lateral assembly
3. Apply bulk density of 1.43 kg/l to determine weight required

Example Calculation:

• Lateral coverage volume needed: 10 litres
• AFM® Grade 3 required: 10L × 1.43 kg/l = 14.3 kg (approximately 1 × 21kg bag)

⚠️ Note: Please consult manufacturer guidelines or contact us for assistance with your specific filter configuration. Dryden Aqua provides detailed filter layering guidance in their Instructions for Use documentation.

💎 Performance Benefits

Verified Filtration Performance

AFM® has been independently tested by IFTS (Institut de la Filtration et des Techniques Séparatives) in France, confirming:

• Double the performance of sand filters without infrastructure changes
• 95% particle removal down to 1 micron with AFM®ng Grade 1
• 98% particle removal down to 1 micron with AFM®s Grade 0
• AFM® closes the gap between conventional media filtration and ultrafiltration

Bio-Resistance Benefits

The activated surface prevents:

• Bacterial colonisation and biofilm formation
• Clumping and coagulation of filter media
• Transient wormhole channelling of unfiltered water
• Biodynamic instability common in sand filters

Operational Advantages

• Up to 50% reduction in backwash water consumption
• Reduced chemical usage due to superior organic removal
• Lower chlorine demand – product water has at least 50% lower chlorine oxidation demand
• Stable, predictable performance throughout the filter’s lifespan
• No media replacement required – lasts for the life of the filtration system

Sustainability Credentials

• Manufactured from 100% recycled bottle glass
• Production is 100% energy and water self-sufficient (solar power and rainwater)
• Circular economy product – can be returned to Dryden Aqua for remanufacturing
• Many installations still performing after 20+ years

🎯 Real World Applications

🏊‍♂️ Residential Swimming Pools

AFM® Grade 3 forms the essential support layer in domestic pool filters, ensuring even water distribution and protecting the finer filtration grades above. Combined with Grade 1 and Grade 2, it delivers crystal-clear water with reduced chemical usage.

🏢 Commercial & Public Pools

Independently verified performance makes AFM® the choice of professional pool operators worldwide. The bio-resistant properties are particularly valuable in high-bather-load environments where bacterial control is critical.

🛁 Hot Tubs & Spas

The elevated temperatures in spa applications make bio-resistance even more important. AFM® prevents the bacterial growth that plagues sand filters in warm water, maintaining water quality and reducing maintenance.

🌿 Ponds & Water Features

AFM®’s ability to remove fine particles and organic matter makes it ideal for ornamental ponds and water features where clarity and ecological balance are paramount.

🏭 Water Treatment Applications

Certified for drinking water treatment, aquaculture, and industrial process water. AFM® is used by Scottish Water and water utilities worldwide for municipal and industrial applications.

🔄 Installation Notes

🛠️ Installing AFM® Grade 3 as part of a complete filter media replacement:

Preparation

1. Remove existing media – Completely empty the filter of old sand or glass media
2. Inspect internals – Check laterals or nozzle plate for damage before refilling
3. Half-fill with water – Add water to approximately half the filter depth before adding media to protect internals from falling media

Installation Sequence

1. Add Grade 3 first – Pour AFM® Grade 3 to cover laterals completely (for filters with laterals)
2. Level each layer – Ensure even distribution before adding the next grade
3. Add Grade 2 – Pour support/filtration layer
4. Add Grade 1 – Pour main filtration layer
5. Level final surface – Ensure bed is flat and even

Initial Commissioning

1. Backwash thoroughly – Run backwash at recommended velocity until water runs clear
2. Rinse to drain – 2-3 minutes rinse phase to settle the bed
3. Initial filtration – Monitor pressure differential during first 24 hours

AFM®ng Specific Requirement

⚠️ Important: AFM®ng has a hydrophobic surface that requires wetting before first use. Submerge in water and soak overnight (>12 hours) prior to first backwash, OR rinse to drain for >10 minutes at >15m/h flow velocity.

Professional Installation

For best results, we recommend professional installation by a qualified pool technician, particularly for commercial or complex residential systems.

📥 Downloads & Resources

 IFTS Performance Test Report – Independent laboratory test results comparing AFM to sand and other glass media (PDF) Download IFTS Report

 AFM Product Brochure – Comprehensive overview of benefits, applications, and technology (PDF) Download Product Brochure

 AFM Installation Manual – Detailed installation instructions and technical guidance (PDF) Download Installation Manual

🏆 Why Choose AFM® NG Grade 3?

✅ Proven Technology – Over 200,000 pool installations worldwide with 30+ years of research and development behind it

✅ Independent Verification – Performance tested and verified by IFTS, the global leader in filtration testing

✅ Guaranteed Longevity – 10-year performance guarantee from Dryden Aqua; many installations still performing after 20 years

✅ Complete Bio-Resistance – The only filter media that actively prevents bacterial growth through its self-sterilising surface

✅ Certified Quality – NSF/ANSI/CAN 61 & 372 drinking water certified; UK DWI Regulation 31 approved; ISO 9001, 14001, and 45001 certified production

✅ Sustainable Choice – 100% recycled content with carbon-neutral production; fully circular economy product

🛒 Why Buy From Parts4Tubs?

At Parts4Tubs, we’re passionate about providing you with the highest quality pool and spa components backed by genuine expertise and outstanding service.

✅ UK-Based Business – We’re a real British company based in Northamptonshire, not a faceless online retailer

✅ Expert Knowledge – Founded on the success of buildahottub.com, we understand pool and spa systems inside out

✅ Fast UK Delivery – Stock items dispatched promptly for quick delivery across the UK

✅ Genuine Products – We supply only authentic Dryden Aqua AFM® media, not inferior imitations

✅ Personal Service – When you buy from Parts4Tubs, you’re buying from Andi – a real person who genuinely cares about your project

✅ Technical Support – Need help choosing the right grades or calculating quantities? We’re here to help

✅ Secure Payment – Multiple payment options including all major cards, PayPal, Apple Pay, and Google Pay

✨ Summary

AFM® NG Grade 3 from Dryden Aqua represents the pinnacle of filter support media technology. This 21kg bag of precision-graded, activated glass media (2.0–4.0mm) provides the essential foundation layer that ensures optimal flow distribution in your pool filter. With its self-sterilising, bio-resistant surface, guaranteed 10+ year lifespan, and verified performance from the world’s leading filtration testing institute, AFM® Grade 3 is the professional’s choice for superior, sustainable pool filtration. Combined with AFM® Grade 1 and Grade 2, it forms part of a complete filtration system that doubles the performance of traditional sand – delivering crystal-clear, healthy water with reduced chemical and water consumption.