Domakihub How to Replace Pool Filter Laterals — Step-by-Step
Fix sand passing through your pool returns by replacing worn filter laterals yourself.
Reviewed by Domakihub pool pros · 2026-06-23 · 5 min read
If sand is blowing back into your pool through the return jets, broken or cracked filter laterals are almost certainly to blame. Laterals are the finger-like plastic tubes at the base of your sand filter's standpipe that trap sand while letting clean water pass — when they crack, everything flows through unchecked. The video above walks through the full Hayward lateral swap, and the steps below give you the complete practical guide, especially useful for homes, holiday rentals, and hotel pools in Greece where heavy summer use accelerates lateral wear.
What Are Pool Filter Laterals and Why Do They Fail?
A sand filter works by pushing water down through a bed of silica sand, which traps debris, and then pulling the cleaned water up through a set of laterals at the bottom of the tank before it returns to the pool. Each lateral is a slotted plastic arm, typically 8–12 of them arranged radially around a central standpipe. The slots are just wide enough to let water through but narrow enough to block sand grains.
Over time — usually 5 to 10 years for quality parts, faster under high chlorine levels or if the filter runs dry — the plastic becomes brittle and cracks. UV exposure on the valve head, freezing winters in northern Greece, or accidental impact during a sand change are common triggers. Once even one lateral cracks, sand bypasses the filter bed and reaches the pool.
When to Replace vs. Repair
If only one or two laterals are cracked and the rest flex without snapping, replacing individual arms is practical and cheap — lateral sets cost €15–40 depending on brand. However, if the laterals are old, brittle, or if the central standpipe (the vertical tube they attach to) is also damaged, replacing the entire lateral assembly as a unit saves time and avoids a second disassembly in a year. For pool installations serving rental guests or hotel clients, replacing the full assembly is the better choice: downtime is costly and credibility matters.
How to Replace Pool Filter Laterals
- 1
Shut down the pump and relieve filter pressure
Switch off the pool pump at the breaker, not just the timer. Turn the multiport valve to 'Winterize' or 'Recirculate' to release any pressure built up inside the filter tank. Open the manual air-relief valve on top of the filter head and leave it open until you hear hissing stop completely. Attempting to open the tank under pressure is dangerous — even modest water pressure can eject the collar or valve head violently.
- 2
Remove the valve head and drain the tank
Disconnect the plumbing unions at the multiport valve (or cut unions if they are glued). Unscrew or unclamp the valve head from the top of the filter tank — most Hayward and Astral filters use a union collar that unscrews by hand. Lift the valve head straight up to avoid bending the standpipe. Connect a hose to the drain plug at the bottom of the tank and route the drain water to a suitable discharge point away from the pool area. In Greece, draining to a soakaway or a drain gully rather than directly to ground is advisable.
- 3
Remove the sand and extract the lateral assembly
Scoop out the sand by hand or with a small wet-dry vacuum until you can see and grip the top of the standpipe. Do not use sharp tools that could score the inside of the tank. Once the sand level is below the lateral arms, grasp the standpipe firmly and lift the entire assembly straight out. Lay it on a flat surface. Inspect every lateral: flex each arm gently — cracked ones will open visibly or break off. Check the standpipe for hairline cracks too.
- 4
Fit the new laterals or lateral assembly
If fitting individual laterals, unscrew each arm from the hub (some are threaded, some are push-lock with a quarter-turn), discard the broken ones, and twist in the replacements until snug — do not over-tighten plastic threads. If fitting a full assembly, simply attach the new unit to the standpipe hub per the manufacturer's instructions. Before reinstalling, wrap the very bottom tip of the standpipe with a small plug or tape to prevent sand from entering the pipe while you refill — remove it before final assembly.
- 5
Refill with fresh sand, reassemble, and backwash
Half-fill the tank with water first to cushion the impact of the sand and reduce the risk of cracking the new laterals. Pour in the correct grade of pool filter sand (typically 0.45–0.55 mm silica) to the marked fill line — usually two-thirds full. Seat the valve head back onto the standpipe, close the air-relief valve, reconnect plumbing unions, and restore power. Run a full backwash cycle of 2–3 minutes, then rinse for 30 seconds, before returning the valve to 'Filter'. Check the return jets — no sand should appear.
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FAQ
- How do I know if it is the laterals causing sand in the pool and not something else?
- Sand returning through the jets almost always points to a broken lateral or a cracked standpipe. Confirm by running the pump for 10 minutes, then switching off and watching the returns — if fine sand settles on the pool floor directly in front of the jet, the filter internals are the source. A torn filter sock on a cartridge filter or a split multiport valve gasket can also send debris back, but those are distinct components you can inspect separately.
- How often should pool filter laterals be replaced in Greece's climate?
- In Greece, where outdoor pools often run 6–8 months a year under high UV and chlorine demand, laterals typically last 6–10 years. Pools serving holiday rentals or hotels that operate nearly year-round and backwash frequently may need replacement closer to the 5-year mark. Inspect laterals every time you change the filter sand (every 3–5 years) and replace any that show cracks or brittleness immediately.
- Can I replace pool filter laterals without changing the sand?
- Yes, but it is rarely worth separating the two tasks. You must remove all the sand to access the laterals anyway, and if the laterals have failed, the sand is likely several years old and due for replacement. Fresh sand after a lateral job ensures proper filtration and avoids repeating the whole procedure a year later. Budget around €20–50 for a 25 kg bag of pool-grade silica sand and factor in the convenience of one complete service.