Pentair Quad D.E.

The Quad D.E. is Pentair's D.E. filter with four pleated cartridges where most D.E. filters have a pack of grids. The powder coats the cartridges the same way it coats grids, and the filter backwashes and takes a fresh charge like any D.E. filter. The difference comes when backwashing isn't enough. The cartridges lift out and get hosed down like a cartridge filter's.

It shares a lot with Pentair's grid filter, the FNS Plus: the 21½-inch tank, the tank o-ring, both clamps and, in the 2025 guides, the lid numbers. Sand, cartridge or D.E. covers how the three types compare.

What the Quad 100 buys over the 80

There are three sizes:

• Quad 60: 60 square feet, 6 lb of D.E., rated at 120 gallons a minute
• Quad 80: 80 square feet, 8 lb of D.E., rated at 160
• Quad 100: 100 square feet, 10 lb of D.E., also rated at 160

The 80 and the 100 have the same flow rating, and their turnover figures match gallon for gallon. And 160 isn't the real ceiling. The same catalog page, and the product page, say Pentair doesn't recommend more than 150 gallons a minute. The sell sheet gives both 150. So the 80 and the 100 are 150-gallon filters. The 8-hour turnover Pentair prints for them, 76,800 gallons, assumes 160. At 150 it's 72,000.

What the 100 buys is area: a quarter more cartridge for the same water. Pentair's pitch for its large cartridges is more dirt capacity and less frequent cleaning, and that's where the extra area goes. It's also 7 inches taller and needs 74 inches of clearance above the pad to lift the cartridges out, against the 80's 68. Filter sizing covers matching the area to your pump.

The clamp changed in 2025

Filters built before August 2025 have a spring clamp. Filters built from August 2025 have a cast clamp. Pentair's support page says the clamp tells you which you have. The two clamps are fitted differently:

• Spring clamp: tighten the barrel nut with a 7/8-inch wrench, tap all the way around the clamp with a rubber mallet, and keep going until the spring coils stay touching. Check the coils at least once a month.
• Cast clamp: start the nut by hand while squeezing the clamp with pliers, then tighten it to 16 to 18 ft-lbs with a 3/4-inch socket. The gap between the clamp's ends should be 1/2 to 3/4 inch.

The spring clamp parts fit only the earlier filters. Pentair publishes a guide for each clamp, and the lid numbers differ between them. The 2025-2026 catalog's footnotes date the change September 2025 rather than August. For a filter built around then, go by the clamp you can see.

Whichever you have, the clamp is what holds the lid on. Pentair's warning is that trapped air can launch the lid with deadly force, so follow the startup steps exactly. Open the air relief valve, stand clear, and start the pump. A steady stream should come out of the valve within about 30 seconds. If it doesn't, if water leaks from under the clamp, or if the gauge shows pressure first, cut the power at once. Never adjust the clamp with the pump powered.

It doesn't plumb like other Pentair D.E. filters

Pentair's guide warns that the Quad has a different flow pattern from its other D.E. filters. Check it before plumbing in a replacement filter or valve. Replacing an FNS Plus with a Quad, or a Quad with an FNS Plus, is where that matters.

The valve is sold separately. The guides name four that fit: the 261055 2-inch multiport, the 261173 1½-inch multiport, the 261050 2-inch HiFlow and the 263064 slide valve.

Coating, backwashing and cleaning

The cartridges have to be coated before the filter does its job. Mix the D.E. with water in a bucket and pour it into the skimmer with the pump running and the valve on Filter. Then write down the starting pressure. On a variable-speed pump, the starting pressure depends on the speed, so Pentair's form also asks for the RPM. Compare later readings at that same speed.

Backwash when the gauge reads about 10 psi above the starting pressure, or when the flow drops noticeably. Then coat the cartridges again with a fresh charge.

When backwashing doesn't bring the pressure down, Pentair's order is:

1. Backwash again.
2. Clean the cartridges by hand: lift off the top manifold, take the cartridges out, and hose each one from top to bottom at a 45-degree angle, working between the pleats. Wash out the tank and bottom manifold too.
3. Soak the cartridges.
4. Replace them if the pressure is still high.

If the filter needs cleaning too often, Pentair's answer is to check the amount of D.E. The filter cleaning guide covers the rest, and Pentair's support page allows at least an hour for a full cleaning.

When D.E. gets into the pool

Pentair's guide gives three causes. The first is a torn or damaged cartridge. The second is a damaged screen cap on the air bleed assembly, or a damaged manifold. The third is cartridges that aren't installed properly. They have to stand upright and be held firmly between the top and bottom manifolds. D.E. in the pool walks through finding which it is.

Winter

Where freezing is brief, Pentair's guide says to keep the filter running until it passes. For a longer freeze, drain the filter completely and clean the cartridges. Then store them and the drain plug somewhere they can't freeze, and reassemble the filter. If you blow the lines out with compressed air, open the filter's air relief valve first, or the lid can separate violently.

Where you buy it

Pentair sells the three sizes through dealers as 188592, 188593 and 188594, all on its TradeGrade list. The Quad 60 and Quad 100 also come as EC-188592 and EC-188594 for online sale. There's no online version of the Quad 80.

That split decides the warranty. From a dealer and professionally installed, it's two years, parts and labor. An EC- number bought online gets one year, parts only. And the product page says a TradeGrade number sold online gets only a 60-day limited warranty. So if you find a plain 188593 for sale online, the price is carrying that risk.