Filters

How Much DE to Add After Backwashing

Pounds of DE powder by filter size, for a backwash and for a full cleaning.

Updated November 2026

Short answer

After a backwash, add the amount of DE printed on your filter label. That is roughly 1 pound of DE for every 10 square feet of filter area on most filters and 1.25 pounds on some, so a 48 square foot filter takes 4.8 to 6 pounds. Filter makers call for this full amount after every backwash.

Many pool technicians add a little less, about 80% of the label amount, because a backwash leaves some DE on the grids. Do not go lower than that.

Pool filter guide

Have a sand filter instead? See how to add DE to a sand filter.

How much DE does my filter need?

Pounds of DE powder by DE filter size
Filter size	Label rate 1 lb per 10 sq ft: full charge	80% of that	Label rate 1.25 lb per 10 sq ft: full charge	80% of that
24 sq ft	2.4 lbs	About 2 lbs	3 lbs	2.4 lbs
36 sq ft	3.6 lbs	About 3 lbs	4.5 lbs	3.6 lbs
48 sq ft	4.8 lbs	About 4 lbs	6 lbs	4.8 lbs
60 sq ft	6 lbs	About 5 lbs	7.5 lbs	6 lbs
72 sq ft	7.2 lbs	About 6 lbs	9 lbs	7.2 lbs

Filter makers do not agree on the rate. Several publish 1 lb per 10 sq ft and others 1.25 lb. Find the size and the DE amount on the label on your tank and use that.

Use the full charge after you open the filter and hose the grids clean, because no DE is left inside. Filter manuals call for the same full amount after a backwash. The 80% figure is a common field practice, since a backwash leaves some DE on the grids. If the water does not clear or the pressure climbs quickly, go back to the full amount.

How do I add DE to the filter?

Weigh and mix first. Weigh the DE powder, then stir it into a bucket of water to make a thin, milky slurry. Measure by weight when you can, because DE is light and scoops vary. Have it ready before you restart the pump, because the grids should not run bare for more than a minute or two.
Backwash. Turn the pump off every time before you move the valve handle. Pump off, valve to Backwash, pump on until the sight glass runs clear, pump off, valve back to Filter.
Start the pump and open the air relief valve until water comes out, then close it.
Pour the slurry into the skimmer right away. The pump carries it to the grids.
Check the gauge. Once the DE is in, read the gauge and write the number down. That is your clean pressure.

Pool grade DE contains crystalline silica, which damages the lungs when it is breathed in. Wear an N95 mask when you handle it dry, scoop it gently, keep it out of the wind and get it wet as soon as you can.

What happens if I add too much or too little?

Too little: the grids are not fully coated, dirt lodges in the fabric and the filter needs cleaning sooner. Water may not clear.
Too much: DE packs between the grids, pressure runs high, flow drops and backwashing gets harder.
DE coming back into the pool: a small puff right after adding is normal. A steady stream points to a torn grid or a cracked manifold.

Backwash again when pressure rises 8 to 10 psi above your clean reading.

Frequently Asked Questions

How much DE is in a scoop?

It depends on the scoop, and DE is very light for its size, so a container holds far less DE by weight than you would guess. Weigh one level scoop once on a kitchen scale and you will know for good.

Do I add DE every time I backwash?

Yes. Backwashing flushes most of the DE out with the dirt, so the grids need a fresh coat each time.

How do I find the size of my DE filter?

Check the label on the tank. The model number usually includes the square footage, such as 36, 48 or 60.

Can I add DE through the skimmer with a salt system or heater?

Yes. The DE is caught by the filter grids before the water reaches the heater or salt cell.

Sources

Sand, cartridge or DE?

How each filter type works, how to clean it and how to read your pressure gauge.

Pool Filter Guide DE in a Sand Filter