A thin white film on the floor the morning after you backwash. Brush it and it clouds, and by the next day it's back.
It's tempting to assume a torn grid and order a set. Sometimes that's the answer. But the first cause on Hayward's own list isn't a part at all, and it's one people cause themselves every time they recharge the filter.
Key takeaways
- A cloud right after a recharge is expected. Hayward's Perflex manual draws the line at 30 seconds after a bump.
- Too much DE is the first cause on Hayward's list. A backwash leaves 10 to 20% behind, so recharge a pound lighter if powder comes back.
- Hayward, Jandy and Pentair all name the grid fabric and the manifold. Two of the three add an o-ring at the outlet.
- Where it comes out matters. From the returns, look inside the filter. Through the skimmer or main drain, look at the check valve.
- The dose differs by brand: a 48 square foot filter takes 6 lb on a Hayward, 5 on a Jandy and 4.8 on a Pentair.
First, when did it show up?
Timing sorts this out faster than anything else.
Right after a recharge, a cloud is expected. Hayward's ProGrid manual has a name for it, the pre-coat puff, and names the six-position valve's Rinse setting for pre-coating when a large cloud comes back to the pool. Rinse sends that water to waste instead.
Right after a bump, too, but briefly. On Hayward's Perflex, the bump filter, the manual's line is 30 seconds. If cloudy water keeps returning to the pool for longer than that after regenerating, it's time to clean the filter.
Still arriving days later means something is letting it through. Pentair's troubleshooting row is headed "Diatomaceous Earth Continuously Enters Pool," and that one word is doing the work.
Make sure it's DE. DE is a fine white powder. Filter sand is grit you can feel between your fingers, and a sand filter blowing sand is a different job with different parts.
Too much DE, the cause that isn't a part
Hayward answers this question directly in its knowledge base, and the first cause it lists is "too much DE was added." It puts that first for both of its designs, the vertical grid and the Perflex.
The reason is in a second Hayward answer, on whether a backwash cleans a DE filter. It doesn't, entirely. A proper backwash removes about 80 to 90% of the DE, and Hayward says the rest stays clumped in the corners or caked in the middle, which it calls common.
Hayward's instructions from there:
- After a backwash, add the entire amount the filter recommends.
- If DE comes back into the pool, let it settle and vacuum it to waste.
- The next time you backwash and recharge, use a pound less.
- After the filter has been taken apart and cleaned, go back to the full amount. Disassembly is the only way to get all the old powder out.
Hayward also says to take the filter apart and clean it at least once a year. Jandy says to inspect the grids at least twice a year.
Jandy doesn't list excess DE among the causes of dirt returning to the pool, but it's blunt about it anyway: excess DE will clog the system, so use the amount in the manual.
The dose is on the label, and it isn't the same across brands
| Grid area | Hayward ProGrid | Jandy DEV | Pentair FNS Plus |
|---|---|---|---|
| 24 sq ft | 3 lb | — | 2.4 lb |
| 36 sq ft | 4.5 lb | — | 3.6 lb |
| 48 sq ft | 6 lb | 5 lb | 4.8 lb |
| 60 sq ft | 7.5 lb | 6 lb | 6 lb |
| 72 sq ft | 9 lb | — | — |
Hayward works to an eighth of a pound per square foot. Jandy and Pentair work to about a tenth. On a 48 square foot filter that puts them a pound or more apart, which is exactly the size of Hayward's own correction. A number carried over from one brand's filter will overdose another's.
Hayward's Perflex has its own figures: 4 lb on an EC40, 6 on an EC65A and 7 on an EC75A.
Weigh it rather than scooping it. Jandy and Pentair both describe measuring with a one-pound coffee can, filled level and not packed down. Pentair's 2023 guide spells out that a level can holds only half a pound of DE. The same guide then rounds its can counts up, so six cans for a 24 square foot filter is three pounds against its own figure of 2.4.
Pentair also asks for DE sold and labeled for pools and spas.
When it's a part
Jandy's manual describes the path the water takes. It passes through the coated grids, the clean water goes into the manifold, then down the outlet tube and out of the filter. The powder does the filtering; in Jandy's words, the cloth merely supports it. Every part on the makers' lists sits somewhere along that path after the powder.
| What fails | Hayward ProGrid | Jandy DEV | Pentair FNS Plus |
|---|---|---|---|
| Too much DE | Listed | — | — |
| Torn grid | Listed | Listed | Listed |
| Cracked manifold | Listed | Listed | Listed |
| O-ring at the outlet | Standpipe o-ring | O-ring inside the filter | — |
| Grids not seated properly | — | — | Listed |
| Air bleed screen | — | — | Listed |
Hayward's column comes from its knowledge base. The ProGrid manual's own problem-solving list covers low flow, short cycles and cloudy water, and doesn't mention DE in the pool.
The grids. A tear or a hole in the fabric lets water skip the powder. Hayward's cleaning instruction is a garden hose inside and out, then a careful brush, and never a pressure washer, which can damage the grids. Pentair's is a straight-flow nozzle held at 45 degrees to the element.
The manifold. The collector across the top of the grids, where the filtered water gathers before it leaves. A crack in it is on all three lists.
The o-ring at the outlet. Hayward's name for the pipe is the standpipe, the one the grid cluster sits on, and its manual says to lubricate the outlet elbow o-rings with Jack's 327 before seating the manifold over them. Jandy's reassembly says to inspect the o-ring at the top of the outlet tube for cracks or excessive wear.
Pentair's two extras. The air bleed screen cap on the top manifold should be cleaned out whenever the grids come out, and a damaged one is on the list. Tightening the wing nuts on the manifold too far is the other: Pentair says it can damage the manifold or elements and result in diatomite entering the pool.
Getting the grids back in the right way. Pentair's last cause is elements not installed properly. They have to stand vertically, with the top manifold secured. All three filters carry one short grid in the set, and on an FNS Plus it goes in the position marked SMALL GRID on the locator. Jandy's instruction is that the grids and the outlet tube fit securely into the manifold.
Where it comes out
Most DE comes back through the returns, and that puts the problem inside the filter.
If it's coming back through the skimmer or the main drain instead, look at a different part. Hayward's Perflex manuals give that its own troubleshooting row, DE leaking back to the pool through the skimmer or main drain, and one cause: the filter check valve, worn or stuck open. The Perflex has one built in.
The ProGrid, DEV and FNS Plus parts lists don't include one, and Pentair's FNS Plus manual recommends adding one. A check valve ahead of the filter, it says, will prevent contaminants from draining back into the pool. If your pad has one, it's a part that wears like any other.
The Perflex has its own list
Hayward's bump filter uses flexible fabric tubes instead of flat grids. The manual calls them flex-tubes and the knowledge base calls them fingers. A handle on top regenerates the powder in place, so the filter runs longer between fresh charges. The causes of powder coming back through the returns:
- a tear in one or more flex-tubes
- a rip or hole in the diaphragm gasket, or one that's worn or fits loosely, and Hayward notes that chemicals fed through the suction lines can shorten its life
- loose bolts on the tube nest plates
- a cracked tube sheet, or bad o-rings on the bump shaft, which the knowledge base adds
- and, again, too much DE
The bump has a technique. Stop the pump, then move the handle down slowly and up briskly, three times. Hayward lists bumping incorrectly as a cause of short cycles, and the fix it gives is a slow down stroke and a brisk upstroke.
The flex-tubes, the diaphragm gaskets, the tube sheet bolts and the shaft kit all have their own part numbers, on the Hayward Perflex page for each size.
Fixing it
- 1
Backwash first
Hayward and Jandy both start a teardown with a backwash, which gets most of the dirty powder out before the tank is opened.
- 2
Shut down, vent and drain
Power off at the breaker, valves set so no water can reach the filter, then open the air relief valve and wait until the gauge reads zero. Pull the drain plug.
- 3
Rinse the grids before you lift them
Hayward recommends hosing the grid cluster down with the drain open before you remove it, which flushes out much of the old DE and makes it easier to lift. Rock it slightly to free the manifold from the outlet elbow, then lift it straight up by the handles.
- 4
Inspect everything on the path
Every grid for tears, holes, cracks or other damage, which is Pentair's list. The manifold for cracks. The o-ring where the manifold meets the outlet. On a Pentair, the air bleed screen cap.
- 5
Replace what's damaged
The grids, the manifold and the outlet o-rings all have their own part numbers, on the catalog page for your filter: the Hayward ProGrid, the Jandy DEV or the Pentair FNS Plus. Pentair's Quad D.E. uses four cartridges instead of grids, and its page has those numbers too.
- 6
Reassemble by the book
The short grid goes back in its own position, the manifold seats fully, and the nuts go on snug rather than tight. Then the clamp, to your maker's figure. Hayward torques its clamp nut to 150 inch-pounds with a torque wrench, and Jandy's clamp ring closes to a gap no wider than 1/16 inch.
- 7
Restart and pre-coat with the full amount
Air relief open, stand clear, start the pump, and close the valve when a steady stream of water comes out. Then pre-coat right away with the full amount, through the skimmer with the pump running. This is the one time Hayward says not to cut it. Don't run the filter bare in the meantime: Hayward's limit is a minute or two, Jandy's three minutes, and the Perflex manuals say one.
- 8
Write down the clean pressure
Every maker has you note the starting pressure right after the pre-coat and backwash from there. Pentair adds that on a variable-speed pump the starting pressure depends on the speed, so record the RPM with it.
Then deal with what's already in the pool. Hayward's instruction is to let it settle and vacuum it to waste, which bypasses the filter entirely. Vacuuming to waste covers the valve setting and the water you'll lose doing it.
Handling the powder
Spent DE has rules too. Pentair says to dispose of it according to local codes and ordinances, and the filter comparison covers the places that restrict discharging it to storm drains.
Go deeperThe full cleaning routine for a DE filterBackwashing, recharging and the soak that brings the pressure back down.Frequently asked questions
Why is DE coming back into my pool?
Hayward's list for a vertical grid filter is short: too much DE added, a tear in a grid, a crack in the top manifold, or a bad o-ring on the standpipe the grid cluster sits on. Jandy's manual blames a hole in the grid fabric, a worn o-ring inside the filter or a cracked manifold. Pentair's names a torn element, a damaged air bleed cap screen or manifold, or elements that weren't put back in properly.
Is it normal to see DE in the pool after backwashing?
A puff just after you recharge is. Hayward's ProGrid manual calls it the pre-coat puff, and its Perflex manuals say cloudy water after a bump shouldn't last more than 30 seconds. If a film keeps building on the floor for days, Hayward's first suggestion is that too much went in: vacuum it to waste and use a pound less next time.
How much DE do I put back after backwashing?
The amount on your filter's label, which varies by brand. A 48 square foot filter takes 6 lb on a Hayward ProGrid, 5 on a Jandy DEV and 4.8 on a Pentair FNS Plus. Hayward says a backwash removes about 80 to 90% of the old DE, so if powder comes back after a full charge, cut the next one by a pound. After a full teardown, go back to the full amount.
How do I get DE out of the pool?
Let it settle, then vacuum it to waste, which is Hayward's instruction. The Waste setting bypasses the filter and sends the water out of the pool. You lose water quickly doing it, so keep a hose running and watch the level at the skimmer.
Is DE dangerous to handle?
The dry powder is. Pentair tells you to wear a NIOSH or MSHA approved dust mask and safety glasses, and warns that handling it improperly could cause serious injury. Jandy says the dust can irritate the eyes and lungs, and that breathing heavy concentrations over time may cause lung damage. Both mix it into a slurry with water before it goes into the skimmer.
