💧 Calplas HFS-20 720mm Side Mount Sand Filter – Up to 94,000 Litre Pool Capacity

Superior filtration performance for pristine swimming conditions all season long

🏊 Product Overview

The Calplas HFS-20 is a high-performance industrial-quality polyester sand filter engineered for larger residential and light commercial pool applications. Featuring a substantial 720mm diameter tank constructed from hand-laid glass reinforced polyester (GRP) with internal steel reinforcement, this Spanish-manufactured filter delivers exceptional durability and filtration performance.

The HFS series stands apart with its significantly taller design, containing almost 50% more filter medium than comparable standard filters. This increased filter bed depth provides extended water contact time, resulting in superior filtration efficiency and enhanced flocculation for consistently crystal-clear pool water throughout the swimming season.

As part of the HFS-15 and above range, the HFS-20 benefits from a larger 305mm transparent filter cover and contains approximately 20% more filter medium than smaller models. The integrated special AFM diffusor ensures ideal water distribution across the filter bed, preventing crater formation and channelling for uniform, effective filtration. With capacity for pools up to 94,000 litres using an 8-hour turnover, the HFS-20 is the ideal choice for larger family pools and demanding applications where water quality is paramount.

✨ Key Features

✅ Industrial-Grade GRP Construction – Hand-laid glass reinforced polyester tank with internal steel reinforcement, manufactured to EN 13121-3 standards

✅ 50% Greater Media Capacity – Taller tank design provides almost 50% more filter medium than standard filters for enhanced filtration performance

✅ Large 305mm Transparent Lid – Oversized inspection port allows easy visual monitoring of filter media condition and water flow

✅ Integrated AFM Diffusor – Special water distribution system ensures even flow across the filter bed, preventing channelling and crater formation

✅ 2.5 Bar Operating Pressure – Industrial-rated pressure handling with 3.75 bar test pressure (7 bar versions available on request)

✅ 6-Way Valve Compatible – Accepts exclusive Calplas 6-way multiport valve with automatic or manual selection; Besgo backwash valve fits as standard

✅ Dual Media Compatibility – Optimised for both traditional sand/gravel and advanced AFM activated filter media

✅ 40°C Temperature Rating – Suitable for heated pools and warm climate installations

✅ Complete Package – Supplied with pressure gauge, air vent, drain plug, and large transparent lid as standard

✅ 5-Year Tank Warranty – Comprehensive manufacturer warranty for long-term peace of mind

✅ Alternative Colour Option – Also available in white to suit installation aesthetics

⚙️ Technical Specifications

Specification	Value
Filter Type	Sand / AFM Media Filter
Tank Diameter	720 mm
Overall Height	1,140 mm
Filter Area	0.39 m²
Flow Rate (Normal Filtration)	11.7 m³/h (at 30 m³/h/m²)
Flow Rate (Backwash Capacity)	19.5 m³/h (at 50 m³/h/m²)
Pool Capacity (6-hr Turnover)	Up to 70,000 litres
Pool Capacity (8-hr Turnover)	Up to 94,000 litres
Sand Capacity	13 kg sand + 3 kg gravel
AFM Media Capacity	8 × 21 kg bags Grade 1 + 8 × 21 kg bags Grade 2
Maximum Operating Pressure	2.5 bar
Test Pressure	3.75 bar
Temperature Rating	Up to 40°C
Inlet/Outlet Connections	2″ (50 mm) threaded
Filter Opening Diameter	305 mm
Distance from Ground	360 mm
Distance Between Connections	190 mm
Tank Material	Hand-laid GRP (Glass Reinforced Polyester)
Reinforcement	Internal steel reinforced
Weight (Empty)	51 kg
Valve Type	Side mount (6-way valve optional)
Warranty	5 years (tank)
Product Code	1519250120
Manufacturer	Calplas (Spain)
Manufacturing Standard	EN 13121-3

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📐 Pool Sizing Guide

Sizing Principle: The filter flow rate should turn over the entire pool volume within 6-8 hours for optimal water clarity and hygiene.

Formula:

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

Pool Size Compatibility:

Pool Type	Volume Range	Suitability
🏊 Medium above-ground	20,000 – 40,000 L	✅ Excellent – oversized for reliability
🏊 Large above-ground	40,000 – 70,000 L	✅ Excellent – ideal match
🏠 Small in-ground	Up to 50,000 L	✅ Excellent – generous capacity
🏠 Medium in-ground	50,000 – 70,000 L	✅ Excellent – optimal performance
🏠 Large in-ground	70,000 – 94,000 L	✅ Good – within maximum capacity
🏢 Small commercial	Up to 70,000 L	✅ Good – suitable for light commercial

This Filter:

📍 Normal Filtration Flow Rate: 11.7 m³/h
📍 Maximum Backwash Flow Rate: 19.5 m³/h
📍 Recommended Pool Size: Up to 70,000 litres (6-hour turnover)
📍 Maximum Pool Size: Up to 94,000 litres (8-hour turnover)

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🛠️ Installation Requirements

Plumbing:

Requirement	Specification
Inlet Connection	2″ (50 mm) female thread
Outlet Connection	2″ (50 mm) female thread
Connection Spacing	190 mm between ports
Valve Position	Side mount

Physical Installation:

Requirement	Details
Base	Solid, level concrete pad or paving slabs required
Minimum Height Clearance	850 mm above filter for lid removal and maintenance
Distance from Ground	360 mm (integrated legs)
Access Clearance	600 mm all around for servicing

Pump Compatibility:

⚠️ Important: Filter must be paired with an appropriately rated pump.

Parameter	Specification
Recommended Pump Flow Rate	8 – 12 m³/h
Maximum Pump Flow Rate	Do not exceed 19.5 m³/h
Pump Head	Allow for filter pressure drop in calculations

💡 Tip: Operating at the lower end of the flow rate range improves filtration efficiency. Higher flow rates reduce contact time and filtration performance.

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🔄 Maintenance Guide

Routine Maintenance:

Task	Frequency	Procedure
Check pressure gauge	Weekly	Record baseline; monitor for increases
Backwash filter	When pressure rises 0.5-1 bar	Run until sight glass runs clear (2-3 minutes)
Rinse after backwash	After every backwash	Run for 30-60 seconds to settle media
Inspect transparent lid	Monthly	Check for cracks, seal condition, clarity
Check O-rings and seals	Seasonally	Replace if worn, cracked, or leaking
Inspect media level	Annually	Top up if settled significantly
Full media replacement	5-7 years (sand) / 10-15 years (AFM)	Complete media change

Pressure Gauge Guide:

📊 Clean filter baseline: Record pressure immediately after backwash
📊 Backwash trigger: 0.5-1 bar above your baseline reading
📊 Maximum operating pressure: 2.5 bar – never exceed

Winterisation (UK Climate):

❄️ Essential winter protection steps:

1. Switch off pump and isolate electrically
2. Close inlet and outlet valves
3. Set multiport valve to “Winterise” position or between settings
4. Drain filter tank completely using drain plug
5. Remove drain plug and store indoors
6. Leave air vent open to prevent pressure build-up
7. Cover filter or relocate to frost-free storage if possible
8. Never leave water in filter when temperatures may drop below 0°C

⚠️ Warning: Frost damage caused by residual water is not covered under warranty. Ensure complete drainage before winter.

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🪨 Filter Media Information

Compatible Media Types:

Media Type	Filtration Rating	Lifespan	Key Benefits
Silica Sand	20-40 microns	5-7 years	Cost-effective, proven, widely available
Glass Media	10-15 microns	10+ years	Finer filtration, eco-friendly, lighter
AFM (Activated Filter Media)	1-5 microns	10-15 years	Superior clarity, self-sterilising, chemical reduction
ZeoSand	3-5 microns	5 years	Excellent clarity, ammonia removal

Media Capacity for HFS-20:

Media Type	Quantity Required
Sand + Gravel	13 kg sand (0.4-0.8 mm) + 3 kg gravel (2-4 mm)
AFM Media	8 × 21 kg Grade 1 + 8 × 21 kg Grade 2 (336 kg total)

💡 Recommendation: The HFS-20 includes a special AFM diffusor, making it particularly well-suited for AFM activated filter media. Upgrading to AFM provides filtration down to 1 micron and extends media life to 10-15 years.

Signs Media Needs Replacing:

• Persistent cloudiness despite balanced water chemistry
• Shortened filter cycles between backwashes
• Cloudy water returning to pool during normal filtration
• Media particles appearing in pool water
• Increased sanitiser consumption
• Visible channelling or uneven media surface

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💎 Filtration Performance

Metric	Value
Filter Area	0.39 m²
Filtration Rating (Sand)	20-40 microns
Filtration Rating (AFM)	1-5 microns

Micron Rating Guide:

Rating	Particle Types Removed
40+ microns	Leaves, visible debris, large particles
20-40 microns	Sand, dirt, visible suspended matter
10-20 microns	Fine particles, some algae spores
5-10 microns	Very fine particles, most algae
1-5 microns	Ultra-fine particles, bacteria, all algae types

Enhanced Filtration Design:

The HFS-20’s extended filter bed height delivers almost 50% more media contact time than standard filters. Benefits include:

✅ Superior flocculation of fine suspended particles
✅ Enhanced removal of organic matter
✅ Improved water clarity and sparkle
✅ Reduced chemical consumption
✅ Extended periods between backwash cycles
✅ Better overall water quality

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⚙️ Valve Positions & Functions

The HFS-20 accepts a 6-way multiport valve (sold separately) providing these functions:

Position	Function
Filter	Standard filtration mode – water flows through media to pool
Backwash	Reverses flow to flush debris from media to waste
Rinse	Settles media and clears residual debris after backwash
Waste	Bypasses filter – sends water directly to drain
Recirculate	Bypasses filter – returns water to pool (for chemical mixing)
Closed	Stops all water flow through the valve

💡 Note: The Besgo backwash valve fits as standard on the HFS-20. Coupling set sold separately. Exclusive Calplas 6-way valves available in automatic or manual versions.

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🎯 Ideal Applications

Application	Pool Size	Suitability
🏠 Large residential in-ground	Up to 94,000 L	✅ Excellent
🏠 Luxury home pools	60,000 – 90,000 L	✅ Excellent
🏡 Holiday rental properties	Up to 80,000 L	✅ Excellent
🏊 Large above-ground pools	Up to 70,000 L	✅ Excellent
🏢 Small commercial/communal	Up to 70,000 L	✅ Good
🧖 Large swim spas	Up to 20,000 L	✅ Excellent (oversized)

Best Suited For:

• Larger residential pools requiring professional-grade filtration
• Pool owners prioritising superior water clarity
• Installations where long-term reliability is essential
• Properties where AFM media upgrade is planned
• Pools with higher bather loads or debris exposure
• Replacement of similar-capacity ageing filters

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❓ Frequently Asked Questions

Q: What size pool will this filter handle?

A: The HFS-20 is suitable for pools up to 94,000 litres with an 8-hour turnover, or up to 70,000 litres for optimal 6-hour turnover. With an 11.7 m³/h flow rate, it’s ideal for larger residential and light commercial pools.

Q: How often should I backwash?

A: Backwash when the pressure gauge reads 0.5-1 bar above your clean baseline pressure. This typically occurs every 1-2 weeks during peak season, varying with pool usage, debris levels, and environmental conditions.

Q: What filter media should I use?

A: The HFS-20 accommodates 13 kg sand plus 3 kg gravel, or 16 bags of AFM media (8 × Grade 1 + 8 × Grade 2). The integrated AFM diffusor makes this filter particularly well-suited for AFM media, achieving filtration down to 1 micron.

Q: How long does filter media last?

A: Sand typically requires replacement every 5-7 years as efficiency declines. Glass media and AFM last 10-15 years with proper maintenance. Regular backwashing and balanced water chemistry extend media lifespan.

Q: What pump do I need?

A: Select a pump delivering 8-12 m³/h for optimal filtration performance. Never exceed the filter’s maximum flow rate of 19.5 m³/h. Operating at lower flow rates within the range provides finer filtration.

Q: What warranty is included?

A: The HFS-20 includes a 5-year tank warranty from Calplas. Contact Parts4Tubs for complete warranty terms and conditions.

Q: Is this suitable for saltwater pools?

A: Yes, the GRP (glass reinforced polyester) construction provides excellent resistance to saltwater corrosion. Ensure all connected valves, fittings, and pumps are also saltwater compatible.

Q: What’s the difference between HFS-15 and HFS-20?

A: The HFS-20 has a larger 720mm tank diameter (vs 640mm), greater filter area of 0.39 m² (vs 0.31 m²), higher flow rate of 11.7 m³/h (vs 9.3 m³/h), and handles pools up to 94,000L (vs 74,000L). Choose based on your pool volume.

Q: Is the multiport valve included?

A: No, the 6-way multiport valve is sold separately. The filter accepts Calplas 6-way valves (automatic or manual selection) and Besgo backwash valves fit as standard. Coupling sets required separately.

Q: What’s the maximum operating pressure?

A: Maximum operating pressure is 2.5 bar. The filter is tested at 3.75 bar. Higher pressure versions (up to 7 bar) are available on request for special applications.

📥 Downloads & Resources

📄 Calplas HFS Filter Specifications (PDF) – Complete technical specifications for the entire HFS filter range

🏆 Why Choose the Calplas HFS-20

✅ Exceptional Filtration Capacity – 0.39 m² filter area with 11.7 m³/h flow rate handles pools up to 94,000 litres

✅ 50% More Filter Medium – Extended filter bed provides superior contact time for outstanding water clarity

✅ Industrial-Grade Build Quality – Hand-laid GRP with steel reinforcement manufactured to EN 13121-3 standards

✅ Versatile Media Options – Optimised for both sand and AFM media with integrated diffusor for filtration down to 1 micron

✅ Large 305mm Inspection Port – Easy visual monitoring and maintenance access

✅ Proven Spanish Engineering – Manufactured by Calplas, specialists in professional pool filtration

✅ 5-Year Tank Warranty – Comprehensive manufacturer coverage for confidence and peace of mind

✅ Perfect for Larger Pools – Ideal capacity for substantial residential and light commercial applications

🤝 Why Buy From Parts4Tubs

✅ UK-Based Company – Local expertise and support from pool and spa specialists

✅ Fast UK Delivery – Prompt dispatch to minimise your project downtime

✅ Expert Technical Advice – Professional guidance on sizing, installation, and maintenance

✅ Competitive Pricing – Excellent value on quality pool equipment

✅ Full Warranty Support – Direct manufacturer warranty handling

✅ Easy Returns – 30-day returns policy for complete peace of mind

✅ One-Stop Shop – Filter media, valves, spare parts, and accessories all available

✅ Trusted Supplier – Established retailer of pool, hot tub, and spa equipment

💫 Summary

The Calplas HFS-20 720mm Side Mount Sand Filter delivers professional-grade filtration for pools up to 94,000 litres. Built with robust hand-laid GRP construction and internal steel reinforcement to EN 13121-3 standards, this Spanish-engineered filter features 50% more media capacity than standard filters for exceptional water clarity. With an 11.7 m³/h flow rate, 0.39 m² filter area, and optimisation for both sand and AFM media (achieving filtration down to 1 micron), the HFS-20 is the ideal choice for larger residential pools. Supplied complete with pressure gauge, air vent, large 305mm transparent lid, and backed by a 5-year tank warranty.

Order now for crystal-clear pool water with professional performance.