Filtration Media — Silica Sand
Grain Size: 0.4-0.8 mm
Available options
- Grain Size: 0.4-0.8 mm, 0.8-1.2 mm
Product Code: FM-4-8-25
Category: Filters
Supplied in two grain sizes, 0.4–0.8 mm and 0.8–1.2 mm, in 25 kg bags. Graded silica sand for pool sand filters, 0.4–0.8 mm, 25 kg bag. This is the filtration grade used in all Waterstar residential top-mount filters (Ø500–Ø900 mm / 20"–36") and as the top filtration layer in commercial side-mount filters. Washed and screened so it does not channel or cloud the water; replace the bed every few seasons or when backwash frequency rises. The number of bags depends on filter diameter and bed depth — see the filter data sheet or ask our team.
Volume: 0.015 m³
Availability: Made to order
Frequently asked questions
What do the six positions of the multiport valve do?
Filter (normal running), Backwash (reverses flow to flush the bed to waste), Rinse (re-settles the bed for 20–30 seconds after a backwash), Waste (drains the pool or vacuums heavy dirt straight to drain, bypassing the filter), Recirculate (circulates without filtering, used when dosing) and Closed. Always stop the pump before moving the handle.
Which multiport valve fits my filter?
MPV-T valves are top-mount, for the Waterstar T-series residential filters; MPV-S valves are side-mount. Both come in 1.5 inch and 2 inch — choose the size of your pump and pipework. All are 6-way with a pressure-gauge port; the MPV-T-15 connects to a 50 mm filter tree.
Which sand grade goes where?
0.4–0.8 mm silica sand (FM-4-8-25) is the filtration layer used in every Waterstar filter. 0.8–1.2 mm (FM-8-12-25) is the intermediate layer specified on some commercial filters between the 1–2 mm gravel support bed and the fine sand. Never substitute building sand — it is neither washed nor graded and will channel.
How often should the sand be replaced?
Every few seasons, or sooner when backwash intervals get shorter, the water stays cloudy after a backwash, or the bed has channelled or formed mud balls. Replace the full charge with the grade on the filter's data sheet and rinse the new bed before the first filter cycle.
