A guide to swapping your pool's filter from sand to AFM®
Looking to capitalise on the benefits of an AFM® (Activated Filter Media) by upgrading your existing silica sand pool filtration system? Cue, Chemsol's comprehensive sand to AFM® conversion guide.
Find out what's involved in switching from a standard swimming pool sand filter to an innovative AFM® solution and which factors all pool owners should consider before making this important decision.
How easy is it to swap sand for AFM®?
Switching from sand to AFM® filtration media is relatively simple - especially if you don't intend to install new deep bed filters to use alongside the AFM®.
This is because AFM® is designed to be a direct replacement for sand, helping pool operators to make the switch with ease.
Why change from a sand filter for your pool to one with AFM®?
Among the many benefits of converting sand filters to AFM® are:
Improved water filtration quality
Whether you run a residential or commercial swimming pool, every pool owner wants to create a healthy and enjoyable swimming experience, which starts with ensuring top water quality.
AFM® outperforms traditional sand, especially when it's paired with deep bed filters. While AFM® is bio-resistant and can filter down to a miniscule 1 micron, sand only captures particles down to 20 to 40 microns and lacks the same bio-resistant properties as AFM®.
AFM® is therefore a more effective filtration media for reducing contaminants in the water, preventing bacterial growth, and promoting water clarity.
Higher hygiene standards
Particularly important for pools with high bather loads, the high filtration performance, bio-resistant properties, and self-sterilising features of AFM® help to keep the swimming environment both healthy and hygienic.
As the filtration media offers more effective water cleaning, it plays a vital role in curtailing the spread of harmful by-products (like trichloramines) and lowers the risk of pathogens such as Legionella and Pseudomonas.
Reduced operational costs
Thanks to the incredibly efficient filtration properties of AFM® compared to sand, this filtration media requires less chemical use and manual backwashing to keep the water clean and clear.
As a result, when pool operators swap sand for AFM®, they often see a significant reduction in various long-term operational costs, such as chemical and energy usage as well as
Plus, AFM® is lighter and has a lower density than sand. This means 15% less AFM® (by weight) is required when using it as a direct replacement for sand in a pool filter.
It also lasts between 15-20 years when properly maintained, meaning less frequent media replacement is needed, saving both time and money.
Factors to consider before changing your pool filter
While swapping from sand filtration media to AFM® boasts many benefits, making an informed decision means understanding and weighing up all the relevant factors.
These factors are outlined below:
Media mass: AFM® is considerably lighter than sand (by around 15%) which means pool operators need 15% less media in terms of weight. This means if you were to swap 100kg sand for 100kg of AFM®, the filter would be overfilled. A good rule of thumb is to multiply the amount of sand you would typically use by 0.85 - this will give you a rough idea of how much AFM® to use.
Grade layering: Most sand pool filtration systems utilise just one size or 'grade' of sand - usually the standard #20 silica sand. However, AFM® must be appropriately layered with different grades (varying from coarse to fine) for effective filtration.
Purchase costs: AFM® generally costs more to purchase upfront than sand. While this can be initially off-putting, considering maintenance needs and long-term cost savings can make the swap a worthwhile investment.
Maintenance requirements: Sand needs regular backwashing and often requires replacement every 3-5 years, while AFM® lasts significantly longer (sometimes up to 20 years) and uses 50% less backwash water than sand. This makes AFM® a less labour-intensive and more cost-effective solution in the long term.
Return on Investment (ROI): Alongside having a lifespan that outlasts normal sand, ROI can also be increased over time thanks to the sheer efficiency of the filtration, which results in reduced backwash water usage and lower chlorine demand.
What does converting sand filters to AFM® involve?
While AFM has been specially designed to be a direct replacement for sand in pool filtration systems, a specific process must be followed.
Whether you're planning on doing it yourself, or want to know what steps a professional would take to make this change, learn how to make the switch from sand to AFM® below.
1. Turn off the pump
The first step is always to turn off the pool filter pump and remove the multiport valve. This is an essential step as it prevents extreme pressure release, equipment damage, and flooding while you're making the media swap.
2. Empty out the old sand
Next, the current sand filtration media must be carefully removed by either scooping or vacuuming it out. This must be done gently to help prevent damage to the fragile lateral fingers at the bottom of the tank.
3. Inspect and clean the tank
Once the tank is empty, it can be thoroughly inspected for any damage or signs of wear. If necessary, certain components - such as the lateral fingers - can be replaced at this stage before the new filtration media is added.
Following this inspection and assuming all components are in good, working condition, the tank should be cleaned using a hose. This helps to ensure any remaining silica sand has been completely removed from the area.
4. Add water up to halfway
You should then fill the empty tank about halfway with water. This creates a cushion which protects the delicate laterals from the impact of the new AFM® filtration media.
5. Refill the tank with AFM®
Next, the tank must be refilled with the appropriate amount of AFM®.
While some large commercial or industrial pool water tanks sometimes use graded gravel with multi-sized sand layers, most require the standard #20 silica sand, which has a grain size of between 0.45-0.55mm.
AFM®, on the other hand, must be appropriately layered with specific grades to ensure effective pool water filtration. Coarser grades (Grade 2 or 3) are usually at the bottom, with the finer grades (Grade 1) placed on top.
6. Reassemble and backwash
Finally, the valve can be put back on and a backwash carried out to rinse away any fine dust before initiating regular pool filtering again.
What to expect during and after conversion to AFM®
Converting sand filters to AFM® is a relatively quick and easy job - depending on various factors, such as the size of the facility.
This task can be completed in just a few hours, especially when carried out by a professional.
Once the swap is complete, minimal maintenance is required compared to traditional sand.
Self-sterilising and biofilm-resistant, AFM® needs less frequent backwashing and can last up to two decades before it should be replaced.
When is it best to install a deep bed filter for your commercial swimming pool?
Deep bed filters – pool filters with an extended media bed - can be combined with AFM® to further enhance the excellent filtration capabilities of the media alone.
Thanks to the deeper media bed, which is usually around 1-1.2 metres deep instead of the standard 0.4-0.6 metres, pool operators can create a thicker, longer-lasting deposit of granular media.
With almost double the amount of depth, these pool filters substantially increase water contact time, helping to trap finer microscopic dirt, debris, and pathogens. Plus, more media can hold more dirt, extending the amount of time that can pass between backwashing.
Subsequently, not only does this combination deliver incredibly effective water filtration for a fantastic swimming experience, but it also reduces chemical, water, and energy consumption costs for the pool owner.
This makes deep bed filters a great investment for pool operators who are willing to spend the initial, upfront installation costs of between £950-£3000 in exchange for long-term reductions in operational costs.
Can a deep bed filter be retrofitted to an existing pool filter system?
Yes, in some cases, a deep bed filter can be retrofitted into an existing pool filtration system. However, this process often requires careful planning, professional oversight, and plenty of preparation.
This is because deep bed filters have a taller vertical profile compared to standard beds. This design allows them to accommodate a greater depth of AFM®, but also makes them harder to retrofit.
Subsequently, if your existing pool filter system isn’t suitable for a deep bed filter retrofit, your pool plant room installer will likely recommend a full upgrade.
At Chemsol, we’ll carry out a comprehensive inspection of your pool plant room to help determine whether retrofitting a deep bed AFM® filter into your existing system is a feasible option.
Book your conversion consultation with Chemsol
If you’re still unsure whether converting sand filters to AFM® is the right move for your commercial or private installation, why not speak to the expert engineers at Chemsol?
Our experienced team routinely carries out fast and efficient filter media replacements for all kinds of leisure and water treatment facilities, including leisure centres, hotels, spas, and aquatic organisations.
Whether you’re interested in switching to a deep bed system or would like to learn more about AFM® and how it can support a cleaner and more enjoyable user experience, we offer a wide range of pool filtration packages and services.
Alongside providing a pool filter upgrade to AFM®, our water treatment specialists can also support with pool plant room design, installation, commissioning, and ongoing maintenance.
To book your initial consultation, request a bespoke quote for an AFM® deep bed filtration system upgrade, or simply discuss your requirements with someone who understands, please don’t hesitate to talk to our team.