Pentair / Sta-Rite 24850-0102S System:3 Lower Tank Half (21″ Filter Tank Bottom)
The Pentair / Sta-Rite 24850-0102S is an OEM replacement lower tank half (tank bottom) for select
Sta-Rite System:3 filter systems that use a 21-inch tank. This part restores the structural base of the filter and the
sealing surface where the tank O-ring seats. Its typically replaced when the original lower shell is cracked, warped, leaking, or the
clamp interface is damaged.
Common Compatibility (Verify Your Filter Model)
- Sta-Rite System:3 Modular Media (SM series)commonly listed for S7M120
- Sta-Rite System:3 Modular D.E. (SMD / SD series)commonly listed for S7MD60, S7MD72, S7D75
- Sta-Rite System:3 Sand (SS series)commonly listed for S7S50 (and often referenced on System:3 sand configurations)
System:3 parts vary by tank size (21″ vs 25″) and series. Confirm your tank size and exact model on the filter label and parts diagram.
What This Part Does
- Replaces the lower portion of the filter tank to restore leak-free operation
- Provides the seating surface for the tank O-ring and proper tank alignment
- Supports internal filter modules and plumbing bulkheads (model dependent)
When to Replace the Lower Tank Half
- Hairline cracks, stress fractures, or visible seepage from the tank bottom
- Warping/deformation that prevents the tank O-ring from sealing
- Damage at the clamp/locking interface that prevents safe, even clamping
- Recurring leaks after replacing the tank O-ring and cleaning sealing surfaces
Installation Notes
- Turn off the pump and relieve all pressure at the air relief before opening the filter.
- Inspect the tank O-ring and replace it if flattened, swollen, cracked, or nicked.
- Clean all sealing surfaces thoroughly; debris or scale can cause leaks even with new parts.
- Tighten the clamp evenly per manufacturer procedure (do not over-tighten).
- After restart, check for slow seepage once the system reaches full operating pressure.
Related Products (Aqua Pool Supply)
- 24850-0102S Lower Tank Half (Search)
- System:3 Tank O-Ring / Seal (Search)
- System:3 Clamp / Band Hardware (Search)
- System:3 Air Relief / Gauge Parts (Search)
- Pool-Safe Silicone O-Ring Lubricant (Search)
Maintenance Tips
- Always fully relieve pressure before opening the filter to protect components and sealing surfaces.
- Keep the tank O-ring clean and lightly lubricated with pool-safe silicone lubricant to reduce pinching and leaks.
- If the tank sits in direct sun, provide shade when possible to help extend plastic component life.
- Record your clean starting pressure after reassembly; a rising baseline can indicate restriction or system changes.
