Hayward VLX4001A Stand Pipe & Underdrain Assembly (VL Series Sand Filters)
Hayward VLX4001A is a genuine replacement stand pipe and underdrain assembly for select Hayward VL Series sand filters (commonly referenced for the VL40T32). This internal assembly helps route water through the filter bed and collect filtered water for return to the pool. Replace it if the original underdrain/standpipe is cracked, broken, or allowing sand to pass into the pool.
Key Features
Part Number: VLX4001A
Brand: Hayward
Type: Sand filter internal stand pipe & underdrain assembly
Designed for compatible Hayward VL Series sand filters (verify model fit before ordering)
Helps support proper filtration flow path and filtered-water collection
Genuine replacement part for proper fit and reliability
Common Symptoms This Part Can Help Fix
Sand returning to the pool through the returns
Reduced filtration performance due to damaged internal collection components
Cracked or broken stand pipe/underdrain discovered during sand change
Internal leakage or poor sealing at the standpipe connection (model-dependent)
Installation Notes
Confirm your exact filter model and internal configuration before ordering (commonly used on VL40T32).
Shut off pump power and relieve filter pressure completely before opening the filter.
Best replaced during a sand change or when the filter is emptied for service.
Inspect the tank for cracks and check for worn O-rings/clamps while the filter is open.
Refill with the correct sand type and amount for your filter model after installation.
Related Products
Hayward VLX4001A
Hayward VL Series Sand Filter Parts
Hayward VLX4002A Clamp Hardware & Tank O-Ring Kit
Pool Filter Sand
Pool-Safe O-Ring Lubricant
Hayward Sand Filter Valve Parts
Maintenance Tips
If you see sand in the pool, inspect the underdrain assembly and laterals (if applicable) during service.
Backwash as needed and avoid over-backwashing, which can reduce filtration quality.
During sand changes, inspect internal parts for cracks or brittleness and replace as needed.
Keep the valve clamp and tank O-ring clean and properly seated to prevent leaks after reassembly.
