🏊 Calplas AFM/P-840 Side Mount Pool Filter – Up to 125,000 Litre Capacity

High-capacity semi-high bed filtration for large residential and commercial pool installations.

🌊 Product Overview

The Calplas AFM/P-840 is a high-performance semi-high bed pool filter engineered for large residential pools and commercial applications demanding superior filtration capacity. Featuring a substantial 840mm diameter tank constructed from hand-laid glass fibre reinforced polyester (GRP), this professional-grade filter delivers impressive water processing capability with its generous 0.52 m² filter area.

With more than double the filter area of the entry-level 520mm model and a robust 900mm filter bed height, the AFM/P-840 handles pools up to 125,000 litres with confidence. The extended media depth ensures exceptional contact time between water and filter media, delivering outstanding water clarity whether using traditional sand or advanced AFM® activated glass media.

Manufactured in Spain by Calplas according to EN 13121-3 European standards, this filter is the choice for demanding installations where reliable, high-volume filtration is essential. The steel-reinforced construction, large 305mm service manhole, transparent acrylic lid, and 3″ sight glass make operation and maintenance straightforward. Compatibility with the Besgo automatic backwash valve system offers hands-free filter cleaning for maximum convenience in busy commercial environments.

✨ Key Features

• ✅ Semi-High Bed Design – 900mm filter bed height delivers superior contact time for exceptional filtration performance
• ✅ High-Capacity Filter Area – 0.52 m² surface area provides more than double the capacity of the 520mm model
• ✅ GRP Construction – Hand-laid glass fibre reinforced polyester ensures absolute watertightness and corrosion resistance
• ✅ Steel Reinforcement – Additional steel at high-stress points for exceptional long-term durability
• ✅ AFM® Optimised Diffuser – Special diffuser prevents crater formation for ideal water distribution across the filter bed
• ✅ Large Service Manhole – ø 305mm access with transparent acrylic cover for easy media loading and inspection
• ✅ 3″ Sight Glass – Large sight glass for clear backwash water monitoring
• ✅ Pressure Gauge Included – Factory-fitted gauge for accurate filter condition monitoring
• ✅ Drain Plug & Vent – Complete with all essential fittings for installation and winterisation
• ✅ Besgo Valve Compatible – Works with automatic or manual Besgo backwash valve systems (sold separately)
• ✅ EN 13121-3 Certified – Manufactured to European pressure vessel standards
• ✅ 5-Year Tank Warranty – Comprehensive manufacturer warranty for complete peace of mind

🔧 Technical Specifications

Specification	Value
Filter Type	Semi-High Bed Sand/AFM Filter
Tank Diameter	840 mm
Filter Area	0.52 m²
Filter Bed Height	900 mm
Flow Rate (Standard @ 30 m³/h/m²)	15.6 m³/h
Flow Rate (Backwash @ 50 m³/h/m²)	26 m³/h
Pool Capacity (6-hour turnover)	Up to 93,600 litres
Pool Capacity (8-hour turnover)	Up to 124,800 litres
Inlet/Outlet Connections	2″ Female Thread (F”)
Tank Height	1460 mm
Distance from Ground	440 mm
Connection Spacing	190 mm
Filter Opening at Top	ø 190 mm
Manhole Diameter	ø 305 mm
Sight Glass Size	3″
Maximum Operating Pressure	2.5 bar
Test Pressure	3.75 bar
Maximum Temperature	40°C
Tank Material	GRP (Glass Fibre Reinforced Polyester)
Tank Colour	Blue RAL 5015 (White available on request)
Weight (Empty)	99 kg
Certification	EN 13121-3
Warranty	5 Years (Tank)

📏 Pool Sizing Guide

The AFM/P-840 is engineered for optimal performance with pools requiring a complete water turnover every 6-8 hours. With an impressive standard flow rate of 15.6 m³/h, this filter delivers reliable filtration for large residential pools and commercial installations.

Sizing Formula:

Required Flow Rate (m³/h) = Pool Volume (m³) ÷ Turnover Time (hours)

Pool Size Compatibility:

Pool Type	Volume Range	Suitability
🏊 Large in-ground	70,000-94,000 L	✅ Excellent – fast turnover rates
🏊 Extra large in-ground	94,000-125,000 L	✅ Ideal – optimal 8-hour turnover
🏢 Small commercial	Up to 80,000 L	✅ Excellent – 6-hour turnover achieved
🏢 Medium commercial	80,000-94,000 L	✅ Ideal – reliable 6-hour turnover
🏢 Large commercial	94,000-125,000 L	✅ Good – 8-hour turnover achieved
🏨 Hotel/leisure pools	Up to 100,000 L	✅ Professional performance
🏊 Very large pools	125,000+ L	⚠️ Consider AFM/P-960 model

This Filter:

📍 Standard Flow Rate: 15.6 m³/h
📍 Backwash Flow Rate: 26 m³/h  
📍 Optimal for pools up to: 93,600 litres (6-hour turnover)
📍 Maximum for pools up to: 124,800 litres (8-hour turnover)

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🔌 Installation Requirements

Plumbing Connections:

Requirement	Specification
Inlet Connection	2″ Female Thread (F”)
Outlet Connection	2″ Female Thread (F”)
Valve Position	Side Mount
Connection Spacing	190 mm centre-to-centre

Physical Installation:

Requirement	Details
Base	Solid, level concrete pad required (reinforced recommended)
Total Height	1460 mm
Distance from Ground to Connections	440 mm
Clearance Above	Minimum 600 mm for lid removal and media access
Clearance Around	Minimum 800 mm for maintenance access
Weight Consideration	99 kg empty – ensure adequate base support

Pump Compatibility:

⚠️ Filter must be matched with an appropriate pump for optimal performance.
✅ Recommended pump flow rate: 12 - 15.6 m³/h (standard filtration)
✅ Backwash capable pump: Up to 26 m³/h
❌ Pump must not exceed filter's maximum flow rate of 26 m³/h

Valve Requirements:

The AFM/P-840 is designed for use with the Besgo automatic backwash valve system (available in automatic or manual versions). A coupling set is required and sold separately. The Besgo valve mounts directly to the filter or can be wall-mounted for flexible installation options.

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🔄 Maintenance Guide

Routine Maintenance Schedule:

Task	Frequency	Method
Check pressure gauge	Weekly	Normal operating range: 0.8-1.5 bar
Backwash filter	When pressure rises 0.5-1 bar above clean baseline	Run until sight glass shows clear water
Rinse after backwash	After each backwash	30-60 seconds to settle media
Inspect seals and gaskets	Seasonally	Replace if worn or cracked
Check media level	Annually	Top up if below recommended level
Full media replacement	Every 5-7 years (sand) or 10+ years (AFM®)	Replace completely

Pressure Gauge Guide:

📊 Clean filter baseline: 0.8 - 1.0 bar (typical)
📊 Backwash required: When pressure rises 0.5 - 1.0 bar above baseline
📊 Maximum operating pressure: 2.5 bar
⚠️ If pressure exceeds 2.5 bar, stop pump immediately and investigate

Winterisation (UK Climate):

For UK pool owners, proper winterisation is essential to prevent frost damage:

• Fully drain the filter tank using the drain plug
• Remove and safely store the drain plug
• Leave all valves in open position to allow any residual water to drain
• Cover the filter or store in a frost-free location if possible
• Never leave water standing in the filter during freezing conditions
• Inspect all seals before recommissioning in spring

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💎 Filter Media Information

Media Capacity Requirements:

Media Type	Quantity Required
Sand/Gravel (25 kg bags)	16 bags coarse + 7 bags medium + 7 bags fine (30 bags total)
AFM® Glass Media (21 kg bags)	15 bags Grade 1 + 8 bags Grade 2 + 8 bags Grade 3 (31 bags total)

Three-Layer Media Configuration:

The AFM/P-840’s larger capacity requires a three-layer media bed for optimal filtration:

Layer	Sand/Gravel	AFM® Glass Media	Purpose
Bottom (Support)	7 bags coarse gravel	8 bags Grade 3	Supports media, covers laterals
Middle	7 bags medium grade	8 bags Grade 2	Transition layer
Top (Filtration)	16 bags fine sand	15 bags Grade 1	Primary filtration layer

Compatible Media Comparison:

Media Type	Filtration Rating	Lifespan	Key Benefits
Silica Sand	20-40 microns	5-7 years	Economical, widely available
AFM® Glass Media	Down to 1 micron*	10-15+ years	Superior clarity, self-sterilising, reduces chlorine demand
ZeoSand	3-5 microns	5 years	Enhanced clarity, ammonia reduction

*With proper flocculation

Why Choose AFM® Activated Filter Media:

AFM® (Activated Filter Media) is specifically optimised for this filter and offers significant advantages over traditional sand:

• Filters particles down to 1 micron (compared to 20-40 microns with sand)
• Self-sterilising surface prevents bacterial biofilm growth
• Reduces chlorine consumption by up to 50%
• Requires 50% less backwash water
• Maintains consistent performance for 10-15+ years
• Bio-resistant – eliminates trichloramine and chlorine smell
• NSF/ANSI certified for pools and drinking water

Signs Your Media Needs Replacing:

• Poor water clarity despite correct chemical balance
• Increasingly short filter cycles between backwashes
• Cloudy water returning to pool after filtration
• Media visible in pool (indicates lateral damage)
• Filter pressure consistently higher than normal even after backwash

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🔬 Filtration Performance

Performance Metric	Value
Filter Area	0.52 m²
Filter Bed Height	900 mm
Standard Flow Rate	15.6 m³/h @ 30 m³/h/m²
Backwash Flow Rate	26 m³/h @ 50 m³/h/m²

Micron Rating Guide:

Rating	What It Removes
40+ microns	Visible debris, leaves, large particles
20-40 microns	Sand, dirt, visible particles (typical sand filtration)
10-20 microns	Fine particles, some algae spores
5-10 microns	Very fine particles, most algae
1-5 microns	Ultra-fine particles, bacteria (achievable with AFM®)

The AFM/P-840’s semi-high bed design with 900mm media depth provides exceptional contact time, enhancing both mechanical filtration and flocculation processes for superior water clarity in high-volume applications.

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⚙️ Besgo Valve Functions

The Calplas AFM/P-840 is designed for use with the Besgo automatic backwash valve system, offering simplified operation compared to traditional multiport valves:

Function	Description
Filter	Normal filtration mode – water flows through media bed
Backwash	Reverse flow cleans media – automated switching available
Rinse	Settles media after backwash (on applicable models)

Besgo Valve Advantages:

• ✅ Automatic backwash capability with timer control
• ✅ No need to stop pump during valve operation
• ✅ Fail-safe design returns to filter mode on power failure
• ✅ Operates in under 2 seconds
• ✅ Silent operation with no pressure hammer
• ✅ Low pressure loss for efficient backwashing
• ✅ Wall or filter-mounted installation options

💡 Note: The Besgo valve and coupling set are sold separately. Contact Parts4Tubs for compatible options.

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🎯 Ideal Applications

Application	Pool Size	Suitability
🏊 Extra large in-ground pools	80,000-125,000 L	✅ Excellent choice
🏢 Commercial swimming pools	Up to 94,000 L	✅ Professional 6-hour turnover
🏨 Hotel and leisure pools	Up to 100,000 L	✅ Ideal for guest facilities
🏫 School and college pools	Up to 94,000 L	✅ Reliable institutional use
🏡 Luxury estate pools	Up to 100,000 L	✅ Premium residential performance
🏢 Holiday park pools	Up to 94,000 L	✅ High-use commercial applications
🧖 Large hydrotherapy pools	Up to 80,000 L	✅ Excellent with AFM® media

❓ Frequently Asked Questions

Q: What size pool will this filter handle? A: The AFM/P-840 is suitable for pools up to 124,800 litres with an 8-hour turnover time. For optimal 6-hour turnover, it’s ideal for pools up to 93,600 litres with its 15.6 m³/h flow rate.

Q: How often do I need to backwash? A: Backwash when the pressure gauge reads 0.5-1 bar above the clean baseline reading. This is typically every 1-2 weeks during swimming season, but varies based on pool usage and bather load. Commercial pools may require more frequent backwashing.

Q: What filter media should I use? A: The filter is compatible with silica sand or AFM® glass media. For optimal performance, we recommend AFM® Activated Filter Media which provides filtration down to 1 micron and lasts 10+ years. This model requires a three-layer media configuration: Sand capacity is approximately 750 kg (16+7+7 bags of 25kg). AFM® capacity is 31 bags of 21 kg (15 bags Grade 1 + 8 bags Grade 2 + 8 bags Grade 3).

Q: Why does this model need three grades of media? A: The larger filter tank requires a proper three-layer bed with support gravel/Grade 3 at the bottom covering the laterals, a transition layer in the middle, and the fine filtration media on top. This ensures optimal flow distribution and prevents media migration.

Q: What pump do I need? A: Match with a pump delivering 12-15.6 m³/h for standard filtration. Ensure the pump can provide up to 26 m³/h for effective backwashing. Never exceed the filter’s maximum flow rate. For commercial applications, consider a variable speed pump for energy efficiency.

Q: Is a multiport valve included? A: No, the valve is sold separately. This filter is designed for use with the Besgo automatic backwash valve system (manual or automatic versions available). A coupling set is also required.

Q: How does this compare to smaller models? A: The AFM/P-840 offers 0.52 m² filter area – more than double the 520 model (0.20 m²), 73% more than the 640 (0.30 m²), and 30% more than the 720 (0.40 m²). It handles pools up to 125,000L with its 15.6 m³/h flow rate.

Q: Is this suitable for commercial use? A: Yes, the AFM/P-840 is well-suited for commercial pools, hotels, leisure centres, and schools with pools up to approximately 94,000 litres (6-hour turnover). For larger commercial facilities, consider the AFM/P-960.

Q: What warranty is included? A: The Calplas AFM/P-840 comes with a 5-year tank warranty. Contact Parts4Tubs for full warranty terms and conditions.

📥 Downloads & Resources

📄 Calplas AFM/P Series Technical Datasheet – Complete specifications for all AFM/P models

🏆 Why Choose the Calplas AFM/P-840

• ✅ High Capacity – 0.52 m² filter area handles pools up to 125,000 litres
• ✅ Commercial Grade – Suitable for hotels, leisure centres, and institutional pools
• ✅ Premium Spanish Engineering – Over 50 years of filter manufacturing expertise from Calplas
• ✅ Superior Build Quality – Hand-laid GRP construction with steel reinforcement
• ✅ Outstanding Filtration – 900mm semi-high bed provides extended contact time for crystal clear water
• ✅ AFM® Optimised – Special diffuser designed specifically for activated glass media performance
• ✅ Easy Maintenance – Large 305mm manhole and 3″ sight glass for simple monitoring and servicing
• ✅ Future-Proof Design – Compatible with Besgo automatic backwash for hands-free operation
• ✅ Proven Reliability – EN 13121-3 certified with 5-year tank warranty

🤝 Why Buy from Parts4Tubs

• ✅ UK-based company with local customer support
• ✅ Fast UK delivery on all orders
• ✅ Expert advice from pool and spa specialists
• ✅ Competitive pricing on all Calplas products
• ✅ Full warranty support and after-sales service
• ✅ Easy returns within 30 days
• ✅ Compatible filter media, pumps, and spare parts available
• ✅ Besgo valves and coupling sets in stock

Need Help? Contact our team for personalised sizing advice and system recommendations. We’re here to ensure you get the right filter for your pool.

⭐ Summary

The Calplas AFM/P-840 Side Mount Filter delivers commercial-grade filtration for large residential pools and professional installations up to 125,000 litres. With its substantial 840mm GRP tank and 0.52 m² filter area, this Spanish-engineered filter provides more than double the capacity of the entry-level 520mm model whilst maintaining the same outstanding build quality. The 900mm semi-high bed design ensures exceptional water clarity when paired with AFM® activated glass media. Complete with large 305mm service manhole, 3″ sight glass, and Besgo automatic backwash compatibility, the AFM/P-840 is the ideal choice for demanding commercial and large residential pool installations requiring powerful, reliable filtration backed by a 5-year tank warranty.

Order your Calplas AFM/P-840 today and enjoy crystal clear pool water all season long!