Pentair DE Filters — FNS Plus & Quad D.E.
Top Pentair D.E. Pool Filters — Fine Filtration for Crystal-Clear Pool Water
8 products
8 products
Pentair D.E. Pool Filters
Aqua Pool Supply carries Pentair diatomaceous earth (D.E.) pool filters, including the FNS Plus and Quad D.E. series. D.E. filters coat their internal grids with a fine powder that traps the smallest particles of any pool filter type, delivering the clearest water possible. Below you'll find complete D.E. filter systems along with the replacement grids and parts to keep them running.
Pentair D.E. Filter Models
Pentair offers two main D.E. families, each with a different approach to servicing:
FNS Plus (24–60 sq. ft.)
A vertical-grid D.E. filter with curved grids that maximize filtration area for better performance and longer runs between cleanings. The fiberglass-reinforced polypropylene tank resists chemicals and corrosion, and the Service-Ease grid pack lets you service grids one at a time. It includes a continuous internal air relief, top-to-bottom backwash, and 2" plumbing ports for efficient flow.
Quad D.E.
The Quad D.E. combines D.E.-level water clarity with the convenience of a cartridge filter. Four removable D.E. cartridges replace the traditional grid assembly, making cleaning faster and simpler. As an Eco Select model, it flows water efficiently, so it can run on smaller pumps or lower speeds to reduce energy use.
We also stock replacement grids and parts for legacy Pentair D.E. systems, so older filters are easy to maintain.
Why Choose a D.E. Filter?
D.E. filters are the right call when water clarity is the top priority:
- The finest filtration available. D.E. powder captures far smaller particles than sand or most cartridge filters, for noticeably clearer water.
- Efficient flow. Pentair's curved-grid and cartridge-style designs reduce restriction, which pairs well with variable-speed pumps.
- Durable construction. Fiberglass-reinforced tanks stand up to pool chemicals and Arizona sun.
- Worth knowing. Unlike cartridge filters, D.E. systems are cleaned by backwashing and then recharged with fresh D.E. powder, so factor that into your maintenance routine.
Comparing your options? Our guide to pool filter types and top Pentair models breaks down how D.E., cartridge, and sand systems stack up.
Sizing Your Filter
Match the filter's square footage and flow rate to your pump and pool volume. A larger grid area handles a faster turnover, holds more debris, and stretches the time between cleanings. As a rule of thumb, FNS Plus models range from 24 sq. ft. (about 48 GPM) up to 60 sq. ft. for higher-flow systems. If you're not sure which size fits your setup, reach out and we'll help you match the right model.
Maintenance & Replacement
Watch the pressure gauge: when system pressure rises roughly 8 to 10 psi above its clean starting point, it's time to backwash and then recharge the filter with fresh D.E. powder through the skimmer. Once or twice a season, open the tank for a full grid cleaning. Replace grids or D.E. cartridges when the fabric tears or no longer holds powder evenly. You'll find replacement grids, manifolds, and air relief valves to keep your system running season after season.
Explore More Pool Filters
Pentair D.E. filters are one part of our full pool filter selection. If you're weighing other technologies, you can also browse Pentair cartridge filters for low-maintenance, no-backwash operation, or Pentair sand filters for the simplest upkeep.
Shopping locally? Aqua Pool Supply offers same-day pickup in Phoenix, AZ and Las Vegas, NV. Order online or stop by to grab the Pentair D.E. filter that fits your pool.
Pentair D.E. Filter FAQs
What makes a D.E. filter different from cartridge and sand filters?
A D.E. filter coats its internal grids with diatomaceous earth, a fine natural powder that traps much smaller particles than sand or cartridge media. The result is the clearest water of any pool filter type. The trade-off is that D.E. filters need backwashing and a fresh charge of D.E. powder afterward, so they require a bit more attention than a cartridge filter.
Do Pentair D.E. filters need backwashing?
Yes. When pressure climbs about 8 to 10 psi above the clean starting point, you backwash the filter to flush out trapped debris and used D.E., then add fresh D.E. powder through the skimmer. Some areas regulate where D.E. backwash water can be discharged, so check your local guidelines before backwashing.
How much D.E. powder does my filter need?
A common rule of thumb is roughly 1 pound of D.E. powder per 10 sq. ft. of filter area for a full charge after a complete cleaning, and about 80% of that after a routine backwash. For example, a 36 sq. ft. FNS Plus takes around 3.6 pounds. Always confirm the exact amount in your filter's manual.
Should I choose the FNS Plus or the Quad D.E.?
Both deliver D.E.-level clarity. The FNS Plus uses a traditional vertical-grid design with one-at-a-time grid servicing, while the Quad D.E. uses four removable D.E. cartridges for faster, simpler cleaning that feels more like a cartridge filter. If easy maintenance is your priority, the Quad D.E. is often the better fit. If you're unsure, contact us and we'll help you decide.
How often should I clean or replace the grids?
Beyond routine backwashing, open the tank for a full grid cleaning once or twice a season. Replace grids or D.E. cartridges when the fabric tears, frays, or no longer holds powder evenly. You can find compatible grids and parts for most Pentair D.E. models in our parts collection.