Hayward ProSeries Sand Filters Explained: Which Model Fits Your Pool?

Hayward ProSeries sand filters are some of the most recognizable pool filters in the residential pool industry, but the model lineup can be confusing. Similar model numbers can mean very different things. A top-mount filter may include a valve, while a side-mount version may or may not. Some models are designed for above ground pools, some are better suited for in-ground pools, and some ProSeries Plus models are built for larger residential or semi-commercial systems.

This guide breaks down the modern Hayward sand filter lineup, including the S166T, S180T, S210T, S244T, S270T, S310T2, S244S, S310S, S311SXV, S360SX, and S360T2. It also explains what the model numbers mean, which filters include a multiport or slide valve, how top-mount and side-mount designs differ, and how to think about filter size based on pool gallons, flow rate, and system demand.

Hayward W3S166T ProSeries® 16" Top-Mount w/ Valve

Why Hayward Sand Filters Are Still So Popular

Sand filters remain popular because they are simple, durable, and easy to maintain. Instead of cartridges that need to be removed and cleaned by hand, sand filters use a bed of filter sand to trap dirt and debris as pool water passes through the tank. When the pressure rises, the filter is cleaned by backwashing, which reverses water flow through the sand bed and flushes trapped debris out through the waste line.

Hayward ProSeries filters are built around this simple concept, but with design details that make a difference in everyday use. The molded polymeric tank is corrosion-resistant, the internal lateral system helps distribute water evenly through the sand bed, and the VariFlo valve makes it easy to switch between filter, backwash, rinse, waste, recirculate, and closed positions on models that include a multiport valve. For pool owners who want reliable filtration without overly complicated maintenance, a properly sized Hayward sand filter is still one of the most practical options available.

Understanding Hayward Model Numbers

Hayward sand filter model numbers usually tell you the approximate tank size and mounting style. For example, an S244T is a 24-inch top-mount sand filter, while an S244S is a 24-inch side-mount sand filter. The letter at the end matters. A “T” model usually indicates a top-mount valve configuration, while an “S” model usually indicates a side-mount configuration. A “T2” model generally indicates a top-mount version with a 2-inch valve. An “SV” model usually indicates a side-mount version with a slide valve.

The “W3” prefix is also important. Hayward uses W3 model numbers for many open-line products sold through broader retail and online channels. In many cases, the W3 version and the non-W3 version are closely related, but customers should still confirm the exact SKU, valve inclusion, plumbing size, and application before ordering. This is especially important when replacing an older filter because two models can look similar while requiring different valves or plumbing connections.

Top-Mount vs. Side-Mount Hayward Sand Filters

The biggest difference between top-mount and side-mount filters is where the valve connects to the tank. On a top-mount filter, the multiport valve sits directly on top of the filter. This design is compact, common on above ground and residential in-ground systems, and usually easier to install in tight equipment areas. Top-mount models are often sold with the valve included, which makes them simpler for replacement situations where the customer wants a complete filter and valve setup.

Side-mount filters have the valve or plumbing connections on the side of the tank. These models usually provide easier internal access through the top of the filter and are common in larger residential or in-ground installations. Side-mount filters can be a better fit when the plumbing layout is already designed for side connections. However, valve inclusion varies by model. The S244S includes a 1.5-inch VariFlo valve, while the S310S is commonly sold without a valve. That distinction is one of the most important things to verify before buying.

The Current Hayward ProSeries and ProSeries Plus Sand Filter Lineup

The table below summarizes the modern Hayward residential and semi-commercial sand filter lineup, including top-mount, side-mount, ProSeries, and ProSeries Plus models. The gallon ranges are practical sizing estimates, not strict manufacturer limits. Actual sizing should always account for pump flow, plumbing size, pool type, turnover rate, debris load, and whether the pool has added features such as solar heating, spas, fountains, or in-floor cleaning systems.

Is the Hayward S210S Discontinued?

The side-mount S210S / W3S210S is the model that causes the most confusion. It has appeared in older ProSeries side-mount literature and replacement situations, but it is not the main modern 21-inch side-mount option customers should expect to find as a current replacement. If someone is replacing an older S210S because they want the same approximate filter size, the closest modern direction is usually the S210T or W3S210T top-mount filter. If the plumbing setup specifically requires a side-mount configuration, the current practical step up is often the S244S, which is a 24-inch side-mount ProSeries filter with a 1.5-inch VariFlo valve included.

This is where the pool owner's expectations matter. Replacing by tank size is not always the same as replacing by plumbing layout. A pool owner with existing side-mount plumbing may not want to rework everything for a top-mount filter, even if the gallon range is similar. A pool owner who simply needs a modern 21-inch Hayward sand filter may be better served by the S210T. Before choosing a replacement, confirm whether the existing setup is top-mount or side-mount, the plumbing size, the pump flow rate, and whether a valve is already installed.

Does the Hayward S244S Include the Multiport Valve?

Yes. The Hayward S244S is a 24-inch side-mount ProSeries sand filter that includes a 1.5-inch VariFlo multiport valve. This matters because the larger S310S side-mount model is commonly sold without a valve. Both are side-mount ProSeries filters, but they are not packaged the same way. If a customer assumes every side-mount Hayward filter includes a valve, the S310S can create an expensive surprise because the correct side-mount valve must be purchased separately.

For product pages, quotes, and customer service responses, the safest language is simple: the S244S includes a 1.5-inch VariFlo valve, while the S310S / W3S310S is a 30-inch side-mount filter where the valve is not included. For the S310S, customers should verify the correct multiport or slide valve for their plumbing and installation before ordering.

Which Hayward Sand Filter Is Smaller Than the S210?

If a customer needs something smaller than the S210 size class, the main Hayward ProSeries options are the S166T / W3S166T and S180T / W3S180T. The S166T is a 16-inch top-mount filter, and the S180T is an 18-inch top-mount filter. Both are commonly used for above ground pools and smaller residential systems where space and flow requirements are lower.

When choosing between the S166T, S180T, and S210T, the decision should not be based on gallons alone. A slightly larger filter is often beneficial because it can improve filtration performance, reduce how often the filter needs to be backwashed, and provide more capacity as the pool collects debris. Oversizing within reason is usually better than undersizing, especially when the pool has trees nearby, heavy swimmer use, or a stronger pump.

Hayward S244T vs. S244S: What Is the Difference?

The S244T and S244S are both 24-inch ProSeries sand filters, but the valve location is different. The S244T is a top-mount filter, meaning the valve sits on top of the tank. The S244S is a side-mount filter, meaning the valve connects to the side of the tank. Both can be strong options, but they are not interchangeable without considering plumbing layout.

The S244T is often used when a compact top-mount design is preferred or when replacing an existing top-mount filter. The S244S is often used when the equipment pad is already set up for side-mount plumbing or when easier access through the top of the filter is preferred. The key detail is that the S244S includes a 1.5-inch VariFlo valve, which makes it more complete out of the box than some larger side-mount models.

Hayward S310S vs. S310T2: Same Size Class, Different Setup

The S310S and S310T2 are both 30-inch Hayward ProSeries sand filters, but they are configured very differently. The S310S is a side-mount filter and is commonly sold without a valve. The S310T2 is a top-mount filter and includes a 2-inch VariFlo valve. This makes the S310T2 more complete for customers who want a 30-inch filter with a valve included, while the S310S is better suited for installations where the customer or installer wants to choose the correct side-mount valve separately.

For large residential pools, either model can make sense depending on plumbing layout. The S310T2 is usually easier to explain as a complete top-mount package with a 2-inch valve. The S310S requires more attention before ordering because the valve is separate. That does not make the S310S a bad option. It simply means the customer needs to understand exactly what is included and what still has to be purchased.

What Is ProSeries Plus?

Hayward ProSeries Plus filters are larger, heavier-duty sand filters designed for more demanding installations. These models are used in large residential, semi-commercial, and feature-heavy pool systems. Pools with in-floor cleaning systems, attached spas, fountains, water features, solar heating, or higher flow requirements may benefit from the added capacity of a ProSeries Plus filter.

Models such as the S311SXV, S360SX, and S360T2 are built for systems that need more filtration area and stronger flow capability than the standard ProSeries lineup. The S311SXV is a 31-inch side-mount model with a 2-inch slide valve included. The S360SX is a 36-inch side-mount tank where the valve is not included. The S360T2 is a 36-inch top-mount model with a 2-inch VariFlo valve included. These are not usually the first choice for a small backyard pool, but they are important options for larger or more complex systems.

How to Choose the Right Hayward Sand Filter Size

Pool gallons are helpful, but they are only part of the sizing decision. A sand filter should be matched to the pump flow rate, plumbing size, pool volume, turnover goal, and real-world debris load. A pool with heavy tree coverage or frequent use may need more filter capacity than a same-size pool in a cleaner environment. A high-flow pump can also overwhelm a filter that is too small, leading to poor filtration, short filter cycles, and more frequent backwashing.

As a general rule, it is better to choose a sand filter with enough capacity rather than selecting the smallest filter that technically fits the pool volume. A larger filter can hold more dirt before pressure rises, which can reduce maintenance and improve overall water clarity. The key is to stay within the filter’s flow rating and make sure the valve, plumbing, and pump are properly matched.

What Valve Does a Hayward Sand Filter Need?

The correct valve depends on the filter model, valve mounting style, and plumbing size. Top-mount filters typically use a top-mounted VariFlo valve, while side-mount filters use a side-mounted multiport valve or slide valve. The port size also matters. Many smaller and mid-size filters use 1.5-inch valves, while larger models commonly use 2-inch valves. Installing the wrong valve can cause plumbing issues, poor performance, leaks, or an installation that does not line up with the filter body.

This is why the exact model number matters so much. An S244S with a valve included is a very different ordering situation from an S310S with no valve included. A customer replacing an old tank should not assume the old valve will fit the new filter unless the part number, mounting style, and plumbing size are confirmed.

Best Hayward Sand Filter by Situation

For small above ground pools, the S166T and S180T are the most compact options in the ProSeries lineup. For a slightly larger above ground or smaller in-ground system, the S210T provides more filter capacity while still using a familiar top-mount layout. For many standard residential pools, the S244T or S244T2 offers a strong balance of size, performance, and value. For larger pools, the S270T, S270T2, or S310T2 provide more filtration area and stronger flow capability.

For customers who need a side-mount filter, the S244S is an important model because it includes the 1.5-inch VariFlo valve. The S310S is the larger side-mount option, but the valve must be selected separately. For more demanding pool systems, the ProSeries Plus models provide larger tanks and higher flow capacity, with the S311SXV, S360SX, and S360T2 serving large residential and semi-commercial applications.

Common Mistakes When Buying a Hayward Sand Filter

One of the most common mistakes is buying by tank diameter alone. A 24-inch filter and a 30-inch filter may both be Hayward ProSeries models, but they can have different valve requirements and plumbing layouts. Another common mistake is assuming the valve is always included. Some models include a VariFlo multiport valve, some include a slide valve, and some do not include a valve at all.

Customers also sometimes replace an older side-mount filter with a top-mount model without realizing the plumbing will need to be changed. That may still be the right decision, but it should be intentional. Before ordering, verify the current filter model, valve type, plumbing size, pump size, and whether the installation is above ground, in-ground, or semi-commercial.

Final Takeaway

Hayward ProSeries sand filters are reliable, proven filters, but the lineup is not as simple as S210, S244, and S310. The modern lineup includes smaller top-mount models like S166T and S180T, mid-size filters like S210T and S244T, larger top-mount options like S270T and S310T2, side-mount options like S244S and S310S, and ProSeries Plus filters for larger or more demanding systems. The most important buying detail is not just the filter size. It is whether the filter is top-mount or side-mount, whether the valve is included, what size valve it uses, and whether the filter is properly matched to the pump and pool.

For most pool owners, the safest approach is to choose the filter based on the existing plumbing layout, pool size, pump flow, and valve requirements. When replacing an older Hayward sand filter, always confirm the exact model number before ordering. That one step can prevent the most common problems, including missing valves, wrong plumbing connections, undersized filters, and unnecessary installation changes.