🌊 Lacron 18″ Sureflow LSR Side Mount Sand Filter – 50,000 Litre Pool Capacity

Effortless pool maintenance with Britain’s most trusted filtration system, delivering crystal clear water season after season.

💧 Product Overview

The Lacron 18″ Sureflow LSR Side Mount Sand Filter represents over 25 years of British engineering excellence in pool filtration. Manufactured by Waterco Europe, this filter has earned its reputation as the most popular residential swimming pool sand filter sold and installed in Britain, with over a quarter of a million units commissioned across the UK.

Constructed from extremely hard-wearing glass reinforced polyester (GRP), the LSR-18 delivers exceptional filtration performance for permanent in-ground residential swimming pools. The side-mount configuration provides excellent accessibility for both installation and routine maintenance, whilst the included six-position multiport valve offers precise control over all filtration functions. With a maximum flow rate of 8.5 m³/h, this filter is perfectly sized for pools up to 50,000 litres.

The Sureflow design incorporates hydraulically balanced laterals and an efficient underdrain system, making it one of the most cost-effective and reliable filtration solutions on the market.

⭐ Key Features

• ✅ British-Engineered Quality – Manufactured to the highest standards with over 250,000 units installed across the UK
• ✅ Glass Reinforced Polyester Tank – Extremely hard-wearing GRP construction provides exceptional durability and longevity
• ✅ Six-Position Multiport Valve – Complete with Filter, Backwash, Rinse, Waste, Recirculate, and Closed positions for comprehensive control
• ✅ Integrated Pressure Gauge – Pre-fitted 3/8″ gauge for easy monitoring of filter performance
• ✅ Side-Mount Configuration – Convenient access for maintenance without disturbing connecting pipework
• ✅ Large 204mm Clear Lid – Excellent visual display during operation and backwashing
• ✅ UV and Corrosion Resistant – Engineered for long-term outdoor use in all weather conditions
• ✅ Hydraulically Balanced Laterals – Optimised water distribution for maximum filtration efficiency
• ✅ Quick Connect Unions – 1½” (50mm) barrel unions for straightforward plumbing connections
• ✅ Winter Drain Included – Purpose-built drainage for proper winterisation in UK climate
• ✅ 5-Year Tank Warranty – Comprehensive 5 (1+4) year warranty on the filter tank

📊 Technical Specifications

Specification	Value
Filter Type	High-Rate Sand Filter
Model	LSR-18 / Sureflow LSR
Product Code	K222018N
Pool Capacity	Up to 50,000 litres (50 m³)
Maximum Flow Rate	8.5 m³/h
Filter Area	0.16 m²
Tank Diameter	460 mm (18″)
Bed Depth	350 mm
Overall Height	790 mm
Overall Width	475 mm
Media Capacity (Sand)	75 kg
Media Capacity (Glass/Lacronite)	60 kg
Test Pressure	4 bar
Maximum Working Pressure	2.5 bar
Inlet/Outlet Size	1½” / 50 mm BSP
Pressure Gauge Connection	3/8″
Valve Type	6-Position Side Mount Multiport
Clear Lid Diameter	204 mm (8″)
Tank Material	Glass Reinforced Polyester (GRP)
Warranty	5 (1+4) years tank, 1 year components

📏 Pool Sizing Guide

Proper filter sizing ensures your pool water is completely filtered within the recommended turnover period. Industry standards recommend turning over the entire pool volume every 6-8 hours for optimal water quality.

Sizing Principle:

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

Pool Size Compatibility:

Pool Type	Volume Range	Suitability
🏠 Small above-ground	Up to 20,000 L	Excellent – ideal sizing with comfortable margins
🏠 Medium above-ground	20,000 – 40,000 L	Excellent – perfect match for this filter size
🏊 Small in-ground	Up to 30,000 L	Excellent – optimal performance
🏊 Medium in-ground	30,000 – 50,000 L	Good – within maximum rated capacity
🏊 Large in-ground	50,000+ L	Consider larger LSR-20 or LSR-24 model

This Filter:

📍 Flow Rate: 8.5 m³/h
📍 Maximum Pool Capacity: 50,000 litres
📍 Turnover Calculation: 50,000 L ÷ 8.5 m³/h = 5.9 hours (excellent)

💡 Tip: For pools with high bather loads or debris exposure, consider sizing up to the LSR-20 (10 m³/h, 60,000L capacity) for faster turnover times.

🛠️ Installation Requirements

Plumbing Connections

Requirement	Specification
Inlet Connection	1½” (50 mm) BSP Female Thread
Outlet Connection	1½” (50 mm) BSP Female Thread
Valve Position	Side Mount
Connection Type	Quick Connect Barrel Unions (included)

Physical Installation

Requirement	Details
Base	Solid, level concrete slab or equivalent firm surface
Clearance Above	Minimum 500 mm for multiport valve operation
Clearance Around	Minimum 400 mm for maintenance access
Location	Protected from flooding, away from drains and gutters

Pump Compatibility

⚠️ Important: The filter must be correctly matched with an appropriate pump.

• Recommended Pump Flow Rate: 6 – 8.5 m³/h
• Maximum Flow Rate: Do not exceed 8.5 m³/h
• Pump Position: Install foot valve/non-return valve if pump is more than 500 mm above water level

💡 Tip: When pump is installed below water level, isolation valves should be fitted at filter inlet and outlet for maintenance access.

🔄 Maintenance Guide

Routine Maintenance Schedule

Task	Frequency	Details
Check pressure gauge	Weekly	Record baseline reading after clean backwash
Backwash filter	When pressure rises 0.5 bar above baseline	Typically every 1-2 weeks depending on use
Rinse after backwash	After every backwash	10-15 seconds until sight glass clears
Inspect seals and O-rings	Seasonally	Replace if worn or damaged
Check media level	Annually	Top up if media has compacted
Full media replacement	Every 5-7 years (sand)	Replace completely when filter cycles shorten

Pressure Gauge Guide

📊 Clean Filter (Baseline): Record reading after initial startup or backwash
📊 Backwash Required: When pressure is 0.5 bar (50 kPa / 7.2 psi) above baseline
📊 Maximum Safe Pressure: 2.5 bar

Backwash Procedure

1. Switch off pump and close inlet valve
2. Release pressure via air release valve until gauge reads zero
3. Turn multiport valve handle to BACKWASH position
4. Switch on pump – backwash water exits to waste
5. Continue until water in sight glass runs clear (approximately 2-3 minutes)
6. Switch off pump
7. Turn multiport valve to RINSE position
8. Switch on pump for 10-15 seconds until water clears
9. Return valve to FILTER position for normal operation

Winterisation (UK Climate)

❄️ Critical for UK pool owners to prevent frost damage:

1. Switch off pump and close inlet valve
2. Open air release valve and set multiport to winterise position (between Filter and Waste)
3. Remove all drain plugs from filter
4. Drain water completely from all pipework
5. Store drain plugs safely for spring recommissioning
6. Cover filter or store in frost-free location where possible

⚠️ Never leave water in the filter during freezing conditions – frost damage is not covered by warranty.

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🪨 Filter Media Information

Compatible Media Types

Media Type	Filtration Rating	Lifespan	Benefits
Silica Sand (16/30 grade)	20-40 microns	5-7 years	Economical, proven performance, widely available
Glass Media (Lacronite)	10-15 microns	10+ years	Superior water clarity, reduced backwashing
Zeolite	3-5 microns	5 years	Excellent clarity, ammonia removal properties

Media Capacity

• Sand: 75 kg (3 × 25 kg bags)
• Glass/Lacronite: 60 kg
• Recommended Grade: 16/30 silica sand (0.5mm – 1.4mm) or 0.35mm – 0.55mm

💡 Tip: Pea gravel is not required for domestic installations with this filter size. For commercial use or filters 24″ and above, a gravel base layer is recommended.

Signs Media Needs Replacing

• Poor water clarity despite correct chemical balance
• Short filter cycles between backwashes
• Cloudy water returns to pool during filtration
• Increased pressure readings that don’t reduce after backwashing
• Visible channelling or compaction when lid is removed

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🔬 Filtration Performance

Metric	Value
Filtration Rating	20-40 microns (with standard sand)
Filter Area	0.16 m²
Bed Depth	350 mm
Flow Rate	8.5 m³/h

Micron Rating Guide

Rating	What It Removes
40+ microns	Visible debris, leaves, large particles
20-40 microns	Sand, dirt, visible particles, hair
10-20 microns	Fine particles, some algae spores
5-10 microns	Very fine particles, most algae, pollen
Below 5 microns	Microscopic particles (requires glass media)

💡 Upgrade Tip: Switching from sand to glass media (Lacronite) can improve filtration from 20-40 microns down to 10-15 microns for noticeably clearer water.

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⚙️ Valve Positions & Functions

The six-position multiport valve provides complete control over your filtration system:

Position	Function
FILTER	Normal filtration – water passes through media and returns to pool
BACKWASH	Reverses water flow to clean media – dirty water exits to waste
RINSE	Settles media after backwash – water goes to waste briefly
WASTE	Bypasses filter completely – direct to waste for vacuuming or lowering water level
RECIRCULATE	Bypasses filter – water circulates without filtration (for chemical distribution)
CLOSED	Stops all water flow – for pump servicing (never use with pump running)

⚠️ Important: Always switch off the pump before changing valve position. Never operate the valve with the pump running.

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🎯 Ideal Applications

Application	Pool Size	Suitability
🏠 Residential above-ground pools	Up to 50,000 L	Excellent
🏡 Residential in-ground pools	Up to 50,000 L	Excellent
🏠 Garden swim spas	Up to 30,000 L	Excellent
🌊 Water features	Various	Good
🏢 Light commercial (small pools)	Up to 40,000 L	Suitable with appropriate maintenance

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❓ Frequently Asked Questions

Q: What size pool will this filter handle?

A: The Lacron LSR-18 is suitable for pools up to 50,000 litres. With its 8.5 m³/h flow rate, it can turn over a 50,000 litre pool in under 6 hours, meeting industry standards for optimal water quality.

Q: How often do I need to backwash?

A: Backwash when the pressure gauge reads 0.5 bar (7.2 psi) above your clean baseline reading. For most residential pools, this is typically every 1-2 weeks during swimming season, though it varies based on usage and environmental factors.

Q: What filter media should I use?

A: The filter is compatible with 16/30 grade silica sand (75 kg), glass media like Lacronite (60 kg), or Zeolite. Sand is economical and effective; glass media provides finer filtration and longer lifespan.

Q: How long does filter media last?

A: Silica sand typically lasts 5-7 years with proper maintenance. Glass media can last 10+ years. Zeolite typically needs replacing every 5 years.

Q: What pump do I need?

A: Match with a pump delivering 6-8.5 m³/h. Do not exceed the filter’s maximum flow rate of 8.5 m³/h. Over-sizing the pump can force debris through the media and reduce filtration efficiency.

Q: What warranty is included?

A: Waterco provides a 5 (1+4) year tank warranty and 1-year warranty on all other components. The first year is full coverage; years 2-5 are pro-rata.

Q: Do I need to add pea gravel?

A: No. Pea gravel is not required for domestic installations with the 18″ filter. It’s only recommended for commercial installations or filters 24″ and larger.

Q: What are the connection sizes?

A: The filter uses 1½” (50mm) BSP female threaded connections with quick-connect barrel unions included. The pressure gauge connection is 3/8″.

Q: Can I use this filter for salt water pools?

A: Yes. The GRP tank construction is fully corrosion-resistant and suitable for both freshwater and saltwater pools.

Q: How do I winterise the filter?

A: Drain completely, remove drain plugs, and ensure no water remains that could freeze. Store plugs safely and cover or relocate the filter if possible. Never leave water in the filter during freezing conditions.

📥 Downloads & Resources

📄 Lacron Filter Product Brochure – Complete specifications and product range

📄 Lacron Filter User Manual – Full installation and operation guide

📄 Lacron Filter Technical Details – Technical specifications and parts information

🏆 Why Choose the Lacron LSR-18

• ✅ Proven Performance – Over 250,000 units installed across Britain over 25+ years
• ✅ British Engineering – Designed specifically for UK pool conditions and climate
• ✅ Superior Construction – Glass reinforced polyester tank tested to 4 bar for reliable operation
• ✅ Easy Maintenance – Side-mount design and clear lid provide excellent access
• ✅ Versatile Media Options – Compatible with sand, glass, and zeolite for optimal results
• ✅ Complete Package – Includes multiport valve, pressure gauge, and quick-connect unions
• ✅ Comprehensive Warranty – 5 (1+4) year tank warranty for peace of mind
• ✅ Spare Parts Availability – Full range of genuine Lacron spares readily available

🤝 Why Buy from Parts4Tubs

• ✅ UK-Based Company – Local support from Northamptonshire
• ✅ Expert Advice – Specialist knowledge from pool professionals
• ✅ Fast UK Delivery – Prompt dispatch on in-stock items
• ✅ Competitive Pricing – Great value on genuine equipment
• ✅ Full Warranty Support – We handle warranty claims on your behalf
• ✅ Easy Returns – 30-day returns policy for peace of mind
• ✅ Complete Range – Filter media, spare parts, and accessories all available
• ✅ Personal Service – Buy from a person, not just the internet

✨ Summary

The Lacron 18″ Sureflow LSR Side Mount Sand Filter delivers outstanding filtration performance backed by over 25 years of British engineering excellence. With an 8.5 m³/h flow rate suitable for pools up to 50,000 litres, durable GRP construction, and a comprehensive 5-year tank warranty, this filter represents exceptional value for residential pool owners. The complete package includes multiport valve, pressure gauge, and quick-connect fittings – everything needed for professional-grade filtration. Order today and enjoy crystal clear pool water with Britain’s most trusted filter brand.