💦 Calplas DPS 420-2550 AFM Vertical Nozzle Plate Filter – 4.91m² Filter Area

Large-capacity commercial pool filtration with 1.2m deep bed for outstanding water quality

🏊 Product Overview

The Calplas DPS 420-2550 is a large-capacity commercial vertical sand filter engineered for demanding public pools and major leisure facilities. Featuring an impressive 2,550mm diameter tank with 4.91m² of filter area and a 1,200mm deep filter bed, this filter delivers exceptional water clarity when paired with AFM (Activated Filter Media).

Manufactured in Spain by Calplas, a world-renowned filter manufacturer since 1970, this filter is constructed using hand lay-up GRP (glass-reinforced polyester) with steel reinforcement for outstanding durability and longevity. Built to EN 13121-3 European standards, the DPS 420-2550 meets the stringent requirements of large public swimming pools, major leisure centres, competition facilities, and commercial aquatic venues.

With a substantial flow rate of 147.3 m³/h at standard filtration velocity, this filter handles pools up to approximately 884,000 litres with a 6-hour turnover, making it the ideal solution for large-scale commercial installations demanding reliable, high-performance filtration.

🌟 Key Features

✅ 4.91m² Filter Area – Substantial filtration surface providing excellent water treatment capacity for large pools

✅ 1,200mm Deep Filter Bed – Optimised bed depth for superior filtration performance with AFM or sand media

✅ Industrial GRP Construction – Hand lay-up fibreglass reinforced polyester with steel reinforcement for exceptional service life

✅ Vertical Nozzle Plate Design – Steel-reinforced plate with 336 precision nozzles ensuring uniform water distribution

✅ 420mm Service Manhole – Large lateral steel-reinforced access for convenient internal inspection and maintenance

✅ 6-inch Sight Glass – Clear inspection window for monitoring backwash progress and media condition

✅ DN250 Connections – Large flange connections for optimal flow with minimal pressure loss on major installations

✅ EN 13121-3 Certified – Manufactured to European pressure vessel standards for commercial applications

✅ 2.5 Bar Working Pressure – Robust construction with 3.75 bar test pressure (higher options available)

✅ Temperature Resistant to 40°C – Suitable for heated commercial pools and therapy facilities

✅ Integrated Lifting Eyes – Safe handling and installation with built-in lifting points

✅ 5-Year Tank Warranty – Comprehensive manufacturer warranty for complete confidence

📊 Technical Specifications

Specification	Value
Filter Type	Vertical Sand/AFM Filter
Tank Diameter	2,550 mm
Filter Area	4.91 m²
Filter Bed Height	1,200 mm
Flow Rate @ 30 m³/h/m²	147.3 m³/h
Backwash Flow Rate @ 50 m³/h/m²	245.5 m³/h
Connection Size	DN250 flange
Overall Height (H)	2,920 mm
Distance from Ground (A)	925 mm
Distance Between Connections (B)	1,385 mm
Free Space Under Filter	100 mm
Service Manhole	ø420 mm (steel-reinforced lateral)
Top Manhole	165 mm
Sight Glass	6 inch
Number of Nozzles	336
Working Pressure	2.5 bar maximum
Test Pressure	3.75 bar
Maximum Temperature	40°C
Tank Material	Hand lay-up GRP (fibreglass reinforced polyester)
Tank Colour	Blue RAL 5015 (white available on request)
Weight (Empty)	1,435 kg
Manufacturing Standard	EN 13121-3
Warranty	5 years (tank)
Product Code	1519260425

📍 Pool Sizing Guide

Sizing Principle

Commercial pool filters must achieve the required turnover rate specified by health regulations. UK PWTAG guidelines typically require:

• Public leisure pools: 2-4 hour turnover
• Competition pools: 4-6 hour turnover
• Hotel/resort pools: 4-6 hour turnover
• Diving pools: Up to 8 hours

Flow Rate Calculation

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

DPS 420-2550 Pool Capacity

Turnover Time	Maximum Pool Volume	Typical Application
4 hours	Up to 589,200 litres	High bather load public pools
6 hours	Up to 883,800 litres	Standard public/competition pools
8 hours	Up to 1,178,400 litres	Lower use facilities, diving pools

This Filter Suits:

Application	Pool Size	Suitability
🏢 Large public leisure pool	500,000-590,000 L	✅ Excellent (4-hour turnover)
🏨 Major hotel/resort complex	600,000-880,000 L	✅ Excellent (6-hour turnover)
🏊 Competition/Olympic training pool	700,000-880,000 L	✅ Ideal (6-hour turnover)
🏢 Water park main pool	600,000-900,000 L	✅ Excellent
🏫 Large university aquatic centre	500,000-700,000 L	✅ Very good

💡 Tip: For heavily used public pools with high bather loads, ensure your chosen turnover meets or exceeds local health authority requirements.

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🔧 Installation Requirements

Plumbing Connections

Connection	Specification
Inlet/Outlet	DN250 GRP flange (integrated into body)
Venting	1″ F connection provided
Drain	Bottom emptying hole included

Physical Installation

Requirement	Details
Foundation	Solid, level concrete base capable of supporting filled weight
Overall Height Required	Minimum 2,920 mm plus service clearance
Free Space Under Filter	100 mm minimum clearance
Service Access	Adequate space around filter for 420mm manhole access
Headroom	Allow clearance above for lid removal and media loading

Dimensional Reference

Dimension	Value
Tank Diameter	2,550 mm
Overall Height (H)	2,920 mm
Distance from Ground to Centre (A)	925 mm
Distance Between Connections (B)	1,385 mm

Pump Compatibility

⚠️ Important: Filter must be matched with appropriate commercial pump(s).

Operation Mode	Required Flow Rate
Normal Filtration	135-150 m³/h
Backwash	240-250 m³/h

⚠️ Commercial installations typically require variable speed pumps or multiple pump configurations to achieve both filtration and backwash flow rates.

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⚙️ Maintenance Guide

Routine Maintenance Schedule

Task	Frequency	Procedure
Check pressure differential	Daily	Compare inlet/outlet pressures
Monitor sight glass	Weekly	Inspect during normal operation
Backwash filter	When pressure rises 0.3-0.5 bar above baseline	Until sight glass runs clear
Rinse after backwash	After each backwash	60-120 seconds
Inspect manhole seals	Quarterly	Check for wear and leaks
Full internal inspection	Annually	Access via 420mm service manhole
Media replacement	Every 10+ years (AFM) / 5-7 years (sand)	Complete media change

Pressure Gauge Guide

Reading	Status
📊 Clean filter baseline	Record during commissioning
📊 Backwash required	0.3-0.5 bar above baseline
📊 Maximum safe pressure	2.5 bar

Backwash Procedure

1. Stop pool circulation pump
2. Set valve to BACKWASH position
3. Start pump and observe 6-inch sight glass
4. Continue until sight glass runs clear (typically 3-5 minutes)
5. Stop pump
6. Set valve to RINSE position
7. Run pump for 60-120 seconds
8. Stop pump and return to FILTER position
9. Resume normal operation

Winterisation (Seasonal Closures)

• Drain filter tank completely via bottom drain
• Remove and store all drain plugs
• Leave service manhole slightly open to prevent pressure build-up
• Protect from freezing temperatures where possible
• Never leave water in filter during freezing conditions

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💧 Filter Media Information

Recommended Media: AFM (Activated Filter Media)

The DPS 420-2550 is optimised for use with AFM, delivering superior filtration compared to traditional sand.

Media Type	Filtration Rating	Lifespan	Key Benefits
AFM (Activated Filter Media)	Down to 1 micron	10-15+ years	Self-sterilising, bio-resistant, 95% particle removal
Standard Sand (0.4-0.8mm)	20-40 microns	5-7 years	Economical, widely available
Glass Media	5-15 microns	10+ years	Finer filtration than sand

AFM Media Quantities for DPS 420-2550

Grade	Bag Size	Approximate Quantity
AFM Grade 1 (main filtration)	21 kg	240 bags
AFM Grade 2 (support layer)	21 kg	100 bags
AFM Grade 3 (base support)	21 kg	As required

💡 Note: Detailed filling plans for sand and AFM available on request. Contact Parts4Tubs for specific media requirements.

Why Choose AFM Over Sand?

Parameter	AFM	Traditional Sand
Filtration Rating	Down to 1 micron	20-40 microns
Lifespan	10-15+ years	5-7 years
Backwash Water Usage	50% less	Standard
Bacterial Growth	Self-sterilising	Biofilm forms over time
Chlorine Demand	Reduced	Standard
Organic Removal	30%+ more effective	Standard

Signs Media Needs Replacing

• Reduced water clarity despite correct chemical balance
• Shortened filter cycles between backwashes
• Increased pressure differential
• Visible channelling through sight glass
• Excessive media loss during backwash

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💎 Filtration Performance

With AFM Media

Performance Metric	Value
Nominal Filtration	Down to 1 micron (95% particle removal)
Standard Filtration @ 20 m/h	5 microns without flocculation
Enhanced Filtration	Sub-0.1 micron with APF/ZPM coagulation
Organic Removal	30%+ more than sand
Bio-Resistance	100% – prevents biofilm formation

Micron Rating Guide

Rating	What It Removes
40+ microns	Visible debris, leaves, large particles
20-40 microns	Sand, dirt, visible particles (sand filter range)
5-15 microns	Fine particles, some algae spores
1-5 microns	Very fine particles, most algae, bacteria (AFM range)

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🎯 Ideal Applications

Application	Pool Size	Notes
🏢 Large public leisure pools	550,000-880,000 L	Ideal for major municipal facilities
🏨 Major resort/hotel complexes	500,000-800,000 L	Excellent for large hospitality venues
🏊 Competition/Olympic training pools	625,000-880,000 L	Meets international standards
🏢 Water park main pools	600,000-900,000 L	High-capacity commercial use
🏫 University aquatic centres	450,000-650,000 L	Reliable institutional choice
🏥 Large hydrotherapy facilities	350,000-550,000 L	Temperature resistant to 40°C

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🤔 Frequently Asked Questions

Q: What size pool will the DPS 420-2550 handle? A: The DPS 420-2550 provides 147.3 m³/h flow rate at standard filtration velocity (30 m³/h/m²). This suits pools up to approximately 589,000 litres with 4-hour turnover or 884,000 litres with 6-hour turnover, depending on your facility’s regulatory requirements.

Q: How often do I need to backwash? A: Backwash when the pressure differential rises 0.3-0.5 bar above the clean filter baseline. Frequency depends on bather load and environmental factors, but commercial pools typically backwash every 1-3 days during peak season.

Q: What filter media should I use? A: The DPS 420-2550 is optimised for AFM (Activated Filter Media), which provides filtration down to 1 micron and a lifespan of 10-15+ years. Traditional sand can also be used. Contact Parts4Tubs for detailed filling plans.

Q: How much does the filter weigh when filled? A: Empty weight is 1,435 kg. Filled weight depends on media type used. Ensure your foundation can support the total weight including water and media.

Q: What warranty is included? A: The Calplas DPS 420-2550 includes a 5-year tank warranty. Contact Parts4Tubs for full warranty terms and conditions.

Q: Can the filter handle higher pressures? A: Standard rating is 2.5 bar working pressure (3.75 bar test). Higher pressure versions up to 6 bar are available on request for specialist applications.

Q: Is this filter suitable for heated pools? A: Yes, the DPS 420-2550 is temperature resistant up to 40°C, making it suitable for heated commercial pools. Ozone resistance is also available on request.

Q: What pump do I need? A: Match with commercial pump(s) capable of delivering 135-150 m³/h for filtration and 240-250 m³/h for backwash. Variable speed pumps or multiple pump configurations are typically required.

Q: How does this compare to smaller models in the range? A: The DPS 420-2550 offers 20.9% more filter area than the 2340 model (4.91m² vs 4.06m²) and 20.9% higher flow rate (147.3 m³/h vs 121.8 m³/h), with DN250 connections for optimal flow on larger installations.

📑 Downloads & Resources

📄 Calplas DPS-420 Technical Datasheet – Full specifications and dimensional drawings

✅ Why Choose Calplas DPS 420-2550

✅ Proven Heritage – Calplas has manufactured industrial filters since 1970 with installations worldwide

✅ 4.91m² Filter Area – Substantial filtration surface for large commercial pool demands

✅ DN250 Connections – Large flanges for optimal flow on major installations

✅ Superior Construction – Hand lay-up GRP with steel reinforcement for exceptional durability

✅ EN 13121-3 Certified – Manufactured to European pressure vessel standards

✅ Optimised for AFM – 1,200mm deep bed maximises activated filter media performance

✅ Easy Maintenance – Large 420mm service manhole and 6-inch sight glass

✅ 5-Year Tank Warranty – Manufacturer-backed quality assurance

⭐ Why Buy From Parts4Tubs

✅ UK-based company with expert technical support

✅ Fast UK delivery on commercial pool equipment

✅ Specialist advice from pool industry professionals

✅ Competitive pricing on Calplas commercial filters

✅ Full warranty support and after-sales service

✅ AFM filter media and spare parts available

✅ Custom configuration assistance for complex installations

✨ Summary

The Calplas DPS 420-2550 delivers industrial-grade filtration for large commercial pools up to 884,000 litres. With 4.91m² filter area, DN250 connections, 1,200mm deep bed optimised for AFM media, and EN 13121-3 certification, this filter provides professional water treatment for major public pools, leisure centres, and competition facilities. Hand-crafted in Spain with GRP construction and backed by a 5-year tank warranty, the DPS 420-2550 combines Calplas’s 50+ years of expertise with proven filtration technology. Contact Parts4Tubs today for expert sizing advice.