Pentair's filter range splits into cartridge units like the Clean & Clear and DE units like the FNS. They share design language but seal quite differently.
Cartridge filters — Clean & Clear
The main seal is the lid o-ring, disturbed every time you clean the cartridge and therefore the one that fails most. Pentair 87300400 filter lid o-ring
Symptoms: water escaping around the lid rim as pressure builds after startup.
DE filters — FNS and manifold seals
DE filters have an internal manifold that distributes flow across the grids, and it seals independently of the tank. Pentair 59000600 manifold o-ring, outlet pipe
A failed manifold seal does not usually leak outside the unit — instead you get DE powder returning to the pool, because water is bypassing the grids. If you are seeing powder at the returns, look here rather than at the tank band.
Reading the symptom correctly
- Water outside the unit — lid, tank band, or plumbing union o-ring
- DE or sand returning to the pool — internal seal, manifold or standpipe, not a leak
- Water to waste while filtering — valve problem, see our multiport valve guide
For Hayward filter equivalents see our filter tank and lid guide.
Before you reassemble
Seat every o-ring with a thin film of food-grade silicone. Dry rings pinch and take a set. Aqua Flex Food Grade Silicone Lubricant is what ships in our kits.
O-rings only. Never lubricate the polished faces of a mechanical shaft seal.
Beaver Island Parts Company is not affiliated with, endorsed by, or sponsored by any equipment manufacturer named on this page. All brand names, model numbers and part numbers are the property of their respective owners and are used solely to identify the equipment our replacement parts fit.