Swimming Pool Filtration Systems in London
At The Swimming Pool Company, we specialise in designing and installing premium swimming pool filtration systems in London. Clean, safe, and crystal-clear water is at the heart of every luxury pool we build — and that starts with the right filtration.
Our carefully designed systems use sand or cartridge filters paired with the latest automatic chlorine or bromine dosing systems, ensuring perfectly balanced water with minimal effort. Every system is tailored to your pool’s size, usage, and design for flawless results.
Swimming Pool Filtration
Selecting the best swimming pool filtration equipment involves correctly pairing a filter and a pump based on your pool's size and the maintenance preferences. We first choose the filter type, then calculate the required flow rate, and finally select the appropriately sized filter and pump.
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1. Choosing the filter type
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There are three primary types of pool filters, each offering a trade-off between water clarity and required maintenance. ​
Sand filters
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Filtration level: Trap debris down to 20–40 microns, which is less fine than cartridge or DE filters.
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Maintenance: Involves periodic "backwashing," which reverses the water flow to clean the sand. The sand needs to be replaced every 5–10 years.
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Pros: Very durable and the simplest to operate. Requires less frequent cleaning than DE filters.
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Cons: Does not provide the highest level of water clarity. Uses the most water during maintenance due to backwashing.
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Cartridge filters
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Filtration level: Trap debris down to 10–20 microns, offering a finer level of filtration than sand.
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Maintenance: The filter cartridges must be manually removed and hosed off. Larger cartridges require less frequent cleaning.
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Pros: Provides excellent water clarity and does not require backwashing, saving water. Larger cartridge filters can go an entire season without cleaning.
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Cons: More expensive to purchase and requires hands-on cleaning.
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Diatomaceous Earth (DE) filters (that we don't use in the UK any more)
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Filtration level: Trap debris down to 2–5 microns, providing the highest level of water clarity.
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Maintenance: Requires periodic backwashing, after which new DE powder must be added.
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Pros: Produces the cleanest, most sparkling pool water.
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Cons: The most expensive and complex filter type. DE powder is a known carcinogen, and disposal regulations vary by location.
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2. Sizing your filter and pump
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The flow rate is a critical metric for sizing your equipment. It is determined by the volume of your pool and how often you want the water to turn over (circulate through the filter).
Step 1: Calculate your pool's volume
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First, find the total cubic meters of water in your pool.
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For a rectangular pool: Volume=Length×Width×Average Depth
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For a round pool: Volume=π×Radius(squared)×Average Depth
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Step 2: Determine your ideal flow rate
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For a healthy pool, we aim to turn over the entire volume of water at least once every 4 hours. Divide your pool's volume by 4 hours to find the target cubic meters per hour.
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Step 3: Choose the correct pump and filter
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We select equipment with a flow rate that meets or exceeds your ideal flow rate.
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Pump: Select a pump that can achieve at least the ideal flow rate.
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Single-speed pumps are a cheaper upfront option but are much less energy-efficient and noisier.
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Variable-speed pumps are more expensive but offer significant energy savings and quieter operation, making them a wise long-term investment.
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Filter: We will choose a filter with a maximum design flow rate that is higher than your pump's flow rate. In general, a larger filter is better because it requires less frequent cleaning.
3. Consider other equipment
Pool Heaters
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Sizing: A heater's size is measured in British Thermal Units (BTUs) or KiloWatts (kW). The proper size depends on your location and how much you want to extend your swimming season.
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Energy use: Larger heaters require more power. Ensure your gas line or electrical service can support the unit.
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Brand and Compatibility
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Compatibility: While mixing equipment brands is possible, using one brand for all your major equipment simplifies installation and troubleshooting.
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Reputation: The major brands in pool equipment in the UK are Plastica, WaterCo, Pentair, Hayward and Certikin (Fluidra).
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Example calculation
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Pool details:
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Shape: Rectangular
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Length: 10 meters
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Width: 4 meters
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Average Depth: 1.50 m
1. Calculate volume:
10 X 4 X 1.50 =60 cum
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2. Calculate target GPM:
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60 cum / 4 hours = 15 cum/hr
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3. Select equipment:
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Pump: Choose a variable-speed pump that can comfortably deliver 15 cum/hr
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Filter: Select a filter (cartridge or sand) with a maximum flow rating greater than 15 cum/hr. Since larger filters require less cleaning, we usually go for an oversized model.
