Korky vs Fluidmaster

The 400H is Fluidmaster’s PerforMAX fill valve. This listing is part 400H-002-P10, sold by Amazon.com. Fluidmaster rates it for toilets with 2 in. or 3 in. flush valves using 1.28 to 3.5 gallons per flush. That covers most two-piece toilets in houses today.

The feature that sets it apart is a second adjustment. Most fill valves only let you set the tank level. The 400H adds a bowl water level dial on top, so you set how much refill water goes down the overflow pipe into the bowl on its own.

Fluidmaster pre-sets that dial for most toilets. If the bowl looks low, its sheet gives a pencil test. Pour a gallon into the bowl, wait a minute and mark the water line. Then flush. If the valve shuts off before the bowl reaches the line, turn the dial counterclockwise for more water.

The tank level is a separate adjustment screw. Fluidmaster says the tank should fill to about ½ in. below the top of the overflow pipe. Turn the screw clockwise to raise the float and counterclockwise to lower it, then flush to reset.

Height adjusts from 9 to 14 in. with a twist of the body. Fluidmaster’s sheet says the top of the cap should sit about 3 in. above the overflow pipe once it’s in. It also says the overflow pipe must sit at least 1 in. below the lever hole.

Fluidmaster lists a silicone seal, a high-grade plastic body, code approval and CSA certification. It says vortex refill gives a faster bowl refill and a stronger flush. That’s Fluidmaster’s claim, and it doesn’t publish refill times for it.

The warranty is 7 years, limited. Fluidmaster’s warranty sheet voids it if the valve wasn’t installed per the instructions, if parts were over-tightened, or if you used in-tank drop-in cleaners with bleach or chlorine. Hand-tighten the locknut and the supply nut.

My call: buy this one if you don’t know your toilet’s age or flush valve size. Its stated range is the widest of the three valves here. It was new and in stock from Amazon.com when I checked.

The 528MP is Korky’s QuietFILL Platinum fill valve. Korky is a brand of Lavelle Industries in Burlington, Wisconsin, and the listing says the valve is designed and made in Wisconsin. Korky aims it at toilets made since 1994 that use 1.6 gallons per flush or less.

That 1994 line matters. It’s when the federal 1.6 gpf limit for new toilets took effect, so most toilets in houses today fall on the Korky side of it. Korky also says the 528MP is designed for high-efficiency toilets, the 1.28 gpf models.

The feature to look at is the strainer. Korky says it catches sediment in the water and makes the valve serviceable. On a well or an old street main that sends grit, that’s a screen you can clear instead of a valve you replace.

Height adjusts from 8-1/2 to 14 in. on Korky’s spec tab. That’s half an inch lower than either Fluidmaster valve, which helps in low tanks. The Amazon listing says 7.75 to 13.5 in. I used Korky’s number; both are in the conflicts table.

Korky’s sheet sets height by a C/L mark, which goes 1 in. above the overflow. Water should stop about ½ in. below the overflow top. A refill adjuster on the tube sets the bowl refill: counterclockwise for less water, clockwise for more. That’s the opposite direction from the 400H’s bowl dial.

Two install details are easy to miss. The mounting nut goes on beveled side up, hand-tight only. The supply connection gets no sealant or tape, and Korky recommends a flexible supply line. Korky lists a minimum working pressure of 6 psi.

The listing includes a refill tube, metal clip, mounting nut, cone washer, refill adjuster, coupling nut and a tamper-proof key. Korky’s sheet says the key is for plumbers and property managers. Attachments for Mansfield and Kohler overflow tubes come in the box too.

Warranty is 5 years. Korky’s sheet voids it if you use in-tank drop-in cleaners or over-tighten the mounting nut. Korky says the valve is proven the quietest in lab testing, but it doesn’t name the test.

Korky’s 528X, the black-top 2X Long Life valve, carries 10 years and uses Chlorazone II rubber that Korky says lasts twice as long. My call: pay for the 528X in a rental. Both were sold by Amazon.com, new and in stock when I checked.

The 400A is Fluidmaster’s standard universal fill valve, and Fluidmaster calls it the world’s number one selling fill valve. This is the brass shank version, 400A-019-P4. Fluidmaster’s page says it’s best for toilets made before 1994 that use 3.5 to 7 gallons per flush.

That’s the opposite target from the Korky. Older tanks hold more water and dump a bigger flush. If the gpf number stamped on your toilet reads 3.5 or more, this is the valve Fluidmaster built for it.

The brass shank is the threaded stem that passes through the tank hole. Fluidmaster says brass resists corrosion and adds strength there. The shank washer comes pre-installed, which saves fumbling with it inside a wet tank.

Adjustment is simpler than the 400H. There’s one tank water level adjustment, set so the tank fills to about ½ in. below the top of the overflow. There’s no separate bowl dial, so the bowl refill is whatever the refill tube sends into the overflow pipe.

Height adjusts 9 to 14 in. with Fluidmaster’s EZ-Twist. Set it so the cap sits about 3 in. above the overflow pipe. The locknut and the supply nut are hand-tight only. Fluidmaster warns that over-tightening may crack the valve or the tank and flood the room.

The 400A sheet has the clearest debris fix here. Turn off the water, twist the cap loose, hold a cup upside down over the open valve, and cycle the supply on and off a few times. If that doesn’t stop the hiss, the replacement seal is Fluidmaster’s 242.

Watch the warranty when you shop. Fluidmaster’s brass shank page lists 7 years, and its plain 400A page lists 5. The plain 400A page also says it doesn’t fit Glacier Bay or Niagara flapperless toilets or one-piece toilets, and doesn’t replace side-entry valves.

My call: buy the brass shank 400A for an older, bigger tank, and the 400H for anything newer. It was sold by Amazon.com, new and in stock when I checked.

The 2017 is Korky’s Ultra 2X Long Life flapper for standard 2 in. flush valves. Korky says it invented the toilet flapper in the 1950s. This one carries a 10-year warranty, double what Fluidmaster gives the 502.

Korky makes it from Chlorazone II, its own red rubber. The company says that rubber is 2 times stronger than other flappers. It says it resists chlorine, chloramines, bacteria, city water treatment, hard water and well water. Korky doesn’t publish test numbers for those claims.

It’s adjustable. A number dial and a band let you match the flapper to the toilet’s original flush. Korky says it adjusts to 1.28, 1.6, 3.5 and 5 gpf tanks. Matching the original setting, Korky says, cuts water waste by flushing no more than the toilet needs.

The package prints a fit guide by toilet age. Korky lists toilets from 1960 to 2005 as virtually all fitting, and 2005 to the present as most. For a 3 in. opening, it points you to its 3060 flapper. Check your opening before you order.

The package also prints a setting chart by toilet model. It covers tanks from American Standard, Kohler, Gerber, Glacier Bay, TOTO and others. Look up your tank number there before you guess at the dial.

The box holds the flapper, a stainless steel chain and instructions. Korky lists fits for 2 in. flush valves from American Standard, Kohler and TOTO. Kohler canister toilets use a seal, not a flapper, so check yours first; our Kohler canister seal guide covers those.

The 100 Ultra is the same family with Korky’s original Chlorazone rubber. The package lines up the range: Plus 2001 at 5 years, Ultra 100 at 5 years and Ultra 2X 2017 at 10 years.

My call: the 2017 is the flapper to buy for a 2 in. toilet that’s worn out flappers before. Both were sold by Amazon.com, new and in stock when I checked. For more Korky options, see our Korky flapper guide.

The 502 is Fluidmaster’s PerforMAX adjustable 2 in. flapper. The 502P21 listing is the single-pack version, sold by Amazon.com. Fluidmaster pitches it as the fix for a weak flush, a toilet that flushes twice, a running toilet and wasted water.

Its frame is solid, not floppy rubber. Fluidmaster says the solid frame gives the best seal with no twisting. That’s aimed at a flapper that drops crooked onto the seat and leaks into the bowl.

The dial sets how long it stays open. Fluidmaster says turning it to a higher number keeps the flapper open longer for a longer flush. A lower number lets it drop sooner and saves water. Change one number at a time and flush between changes.

Fluidmaster rates it for 1.28, 1.6 and 3.5+ gpf toilets, and the listing says 1.28 to 3.5. It fits most 2 in. flush valves. Fluidmaster’s page has a short FAQ on telling a 2 in. valve from a 3 in. one, and so does our 2 in. vs 3 in. flapper guide.

The listing names Microban and says the rubber resists chlorine and hard water. Fluidmaster’s own page says the same about chlorine and hard water. Its warranty still ends if you use in-tank drop-in cleaners with bleach or chlorine.

The warranty is 5 years. Fluidmaster also packs this flapper in its 555C flush valve repair kit. If the seat under the flapper is pitted or cracked, no flapper will seal it; that’s a flush valve job, covered in our flush valve guide.

Against Korky’s 2017, it gives up five years of warranty and gains the stiff frame. My call: pick the 502 when the flush is weak or doubles, and the 2017 when flappers wear out fast. It was new and in stock from Amazon.com when I checked.