How to Recharge or Refill DE in Pool Filter

Did you just backwash your DE filter and aren’t sure how to refill it? Or perhaps you just cleaned it out or have a new filter? The Diatomaceous Earth (DE) refill process is somewhat detailed, so we’ve outlined the most important facts in this article.

Here’s the short answer.

To refill a DE filter, measure the amount of required DE. You will need about 80% of the total DE capacity if refilling after backwashing. Next mix the DE into a slurry and pour slowly into the skimmer with the filter and pump switched on.

Naturally, there’s a bit more to it than that. Keep reading to see the full process.

Diatomaceous Earth (DE) Pool Filter

Reasons For Refilling DE

Diatomaceous Earth (DE) is a fine white powder, made entirely of fossilized phytoplankton. The particles have a unique nanostructure which allows the DE to catch small contaminants and keep your pool’s water super fresh.

DE is by far the most effective substance for pool filtration because it has the ability to filter out microscopic contaminants. DE becomes gradually contaminated over time and as a result, you need to backwash and purge the DE every month or two. Or when the pressure on your filter rises 25% higher than normal.

After backwashing, you must refill or “recharge” your DE filter with fresh powder.

Refilling the DE is one of the most important maintenance procedures for your pool. This process ensures that the pump and filter are not being over-stressed by keeping the PSI at a good level.

Fresh DE means more effective filtration. In fact, if you ignore the DE for too long, your entire pool may be cloudy or your pump may wear out quicker from the extra pressure.

The most common signs of the DE being spent are:

  • PSI gauge reading is 8-10+ higher than normal (or 25% higher)
  • Water is cloudy

Materials Needed to Refill a DE Filter:

  • 3 to 10 lbs of Diatomaceous Earth
  • Filter Owner Manual (Recommended)
  • Alladin 300 E-Z DE Scoop

Step 1: Empty Old DE (via Backwashing or Deep Clean)

backwash setting
backwash setting

There are two ways to remove the DE from your pool filter:

  • Backwashing
  • Open the Filter

Each pool has a slightly different protocol for backwashing or filter removal. Have a good look at your Owner Manual and decide which method you will be using to purge the dirty DE from your filter.

Backwashing

If you are performing a backwash, the old DE is removed when you turn the power back on with the pump in the reverse/backwash setting. Let the pump run in reverse/backwash mode for 2-3 minutes.

Check out our article for more details: How to Backwash a Filter

Backwash hose

Milliard 50 ft Heavy Duty Backwash Hose, Great for Water Disposal - Weather and Chemical Resistant - 2 inch Diameter

Open the Filter

Unless you’re performing other maintenance, this isn’t necessary. If you do want to inspect the filter grids, which should be done yearly, start by switching off the power at the breaker. Then open the pressure release valve on your filter to release the pressure. Now you can safely open the filter up and scoop out the DE.

Step 2: Determine the Amount of New DE to Use

Pool Filters require anywhere from 3 to 10 lbs (1.5 to 4.5 kg) of DE. DE for Pools is typically sold in 25 and 50-pound bags. The Filter’s Owner Manual will include a recommended amount.

If you cannot access the manual, the general rule is to add 1 lb for every 10 square feet of the filter’s capacity. If you’re lucky, the filter’s capacity will be written on the filter.

 An example would be if you had a 60-square-foot filter, you’d need 6 lbs of DE.

The easiest way to measure the DE is to use the Alladin 300 DE scoop. One scoop is equal to 1 lb of DE. It’s far easier than weighing it.

Blue Devil D.E. Scoop with Handle, Perfect for Swimming Pools

Step 3: Reset Pressure Release and Turn Power Back On

If you opened your filter, you’ll need to close the pressure valve. Now you can switch the power back on but don’t switch the pump on yet.

Step 4: Add New DE

Now with the filter emptied of most or all of the old DE, the fresh DE is gradually added to the pool.

Robelle 4024 D.E./Diatomaceous Earth Powder for Swimming Pools, 24-Pound

Mix the new DE in a bucket with water; 1 part DE to 2 parts water. Slowly pour the DE mixture into the skimmer while the pump is on so the fresh DE can be pulled into the filter. This ensures the even distribution of the new DE into the filter.

  • Keep an eye on the PSI gauge as you gradually add the DE powder. You can stop adding powder once the PSI has reached a normal level.
  • Too much DE will mean the filter efficiency isn’t good. So be cautious and try to catch that perfect PSI.
  • Not enough DE and the filter won’t work properly either.
  • Run the pump for 20-30 minutes to ensure the new DE cycles fully into the filter.

Step 5: Check for Leaks

You should be able to see if your filter is leaking DE. If your filter is old, clogged or malfunctioning, you can often detect DE slowly coming out the return jets or on the pool floor around the return jets. If this is the case, the filter grids may be damaged.

How to Add DE Without a Skimmer

If your pool does not have a skimmer, you can add DE into the suction port of the pool.

To do this, start by locating the suction port on the wall or floor of the pool. Pour the DE into a small container. Switch on the pool filter and pump.

Slowly submerge and offer up the container to the suction port. With some luck, the suction inlet should suck in the DE. You may need to try this a few times with a small amount of DE to make sure your technique works.

What to Do If You Add Too Much DE

If you have added too much DE, you will need to do a series of short backwash flushes until the PSI reaches its normal level. Backwashing will remove some of the DE from the filter.

If your PSI goes too low in this process you will need to add small amounts of DE until the desired pressure is reached.

Further Reading: Too Much DE Added to Filter (How to Remove Excess DE)

Can I Add DE Without Backwashing?

If your filter is new, or you have cleaned it out completely and it doesn’t have any DE already in it, you do not need to backwash before adding DE. If there is already DE in your filter, backwash it first to avoid overfilling it.

When cleaning out your DE filter, you’ll always need to get rid of the old DE by backwashing. Adding a new DE while the filter is full of contaminated DE will provide zero benefits to your pool. Out with the old, in with the new!

Best Type of DE for Pools

Diatomaceous earth comes in different grades. Food grade DE is not suitable for swimming pool filters. Using an incorrect grade of DE will lead to poor filtering, or you may block up the filter completely.

DE branded for pools is always a good option because it is the correct grade and is sold in the right quantity.

How Much DE To Refill a New or Empty Filter?

For a brand new or thoroughly cleaned filter, you can safely add the total amount of DE based on the square foot capacity.

A rule of thumb is to add 1 lb of DE powder for every 10 square feet of filter capacity.  A 60-square-foot filter will need 6 lbs of DE to refill it from empty.

How Much DE to Add After Backwashing

If you are backwashing, you will only need to use 80% of the total amount of DE required. For example, if your filter requires 6 pounds of DE to fill it from empty, then recharge it with 4.8 lbs after backwashing.

This is because the backwashing process leaves a considerable amount of DE in the filter.

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