Hayward ProSeries Sand Filter Inground 21 In Side Mount 1.5 Inch Valve

Hayward ProSeries W3S210S 21-Inch Side-Mount Sand Filter for In-Ground Pools

The W3S210S delivers the same filtration performance as the W3S210T — 21-inch tank, 200 lbs of sand, 44 GPM, 2.20 sq ft — with one meaningful difference: the multiport valve mounts at the side of the tank rather than the top. This lowers the overall installation height, which matters in equipment rooms with limited overhead clearance, under-deck installations, or any setting where the top of the filter is close to a ceiling, beam, or lid.

The side-mount configuration also puts all valve controls at a comfortable working height without reaching overhead, which some installers and service technicians prefer for routine backwash operations. If overhead clearance is not a constraint, the top-mount W3S210T is equally capable at the same price point.

Hayward W3S210S ProSeries 21-Inch Side-Mount Sand Filter Key Features

• Side-mount 1.5" Vari-Flo valve - Positions all 7 operating modes at the side of the tank for lower total installation height and comfortable eye-level access. Filter, Backwash, Rinse, Waste, Recirculate, Closed, and Winter positions with integral sight glass.
• Reduced installation height - The side-mount configuration is the practical choice for low-clearance equipment rooms, under-deck settings, or installations near overhead obstructions that would prevent a top-mount valve from fitting.
• 21-inch corrosion-proof tank - Same reinforced thermoplastic construction as the top-mount model. UV-stable, colorfast, and rated for permanent outdoor installation.
• Umbrella-fold self-cleaning laterals - 360-degree slotted laterals deliver balanced, energy-efficient backwashing across the full base of the sand bed.
• Integral top diffuser - Even water distribution across the sand surface on entry for maximum use of the full filtration area.
• Large pressure sand/water drain - Full-size base drain for fast seasonal draining and sand changes.

Hayward W3S210S ProSeries 21-Inch Side-Mount Sand Filter Specifications

Sand not included. Use #20 grade silica pool filter sand only.

Hayward ProSeries In-Ground Sand Filter Lineup: W3S210S in Context

Flow rates and filtration areas per Hayward published specifications. The W3S310S does not include a valve; a compatible backwash valve must be purchased separately.

Maintaining the Hayward W3S210S ProSeries 21-Inch Side-Mount Sand Filter

Backwash when pressure rises 8 to 10 PSI above the clean baseline recorded at first startup. Switch to Backwash until the sight glass clears, Rinse for 15 to 30 seconds, then return to Filter. Replace sand every 3 to 5 years or sooner if persistent cloudiness, fine sand at the return fittings, or very short backwash intervals develop.

First Startup: Loading Sand

Fill the tank halfway with water before adding sand to cushion the lateral assembly. Add 200 lbs of #20 silica sand gradually and evenly. Run a full Rinse cycle before switching to Filter to clear fine dust from the new media. Record the post-Rinse pressure as the clean baseline.

Winterizing the W3S210S

Backwash before shutdown. Drain the tank through the base drain and leave the plug out. Set the valve to Winter to drain the valve body. In hard-freeze climates, blow out the valve body with compressed air for additional protection against cracking.

Hayward W3S210S ProSeries 21-Inch Side-Mount Sand Filter Frequently Asked Questions

Hayward W3S210S ProSeries Sand Filter Documentation