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How To Clean And Backwash A DE Pool Filter (The Right Way)

DE filters (diatomaceous earth) are the best pool filters money can buy, removing pollutants in your pool as small as 1 micron in size.

But like all things related to pool maintenance, they’ll eventually get dirty and need to be cleaned. 

A clean DE pool filter is a top performing filter, and we’ve simplified how to clean it out below.

Why Clean Your DE Filter?

Over time, pollutants from debris in the water will accumulate on the DE filter grids, making it less effective the longer it goes uncleaned. This can lead to a range of pool issues like cloudy water and algae blooms.

The grids in a DE filter can last anywhere from 3 to 5 years, although some people stretch that lifespan as much as they can. At any rate, regular cleaning of the filter grids will prolong their life and keep the pool water clean.

Compared to sand filters and cartridge filters which require cleaning every few weeks, DE filters can last a few months before needing to be cleaned.

How To Clean Your DE Filter

Every 1 to 3 months, you’ll need to clean, or “recharge”, your DE filter.

DE filters, like sand filters, can be backwashed. However, they also need to be disassembled every time, for a thorough cleaning. This is to ensure there is no build up of debris on the manifold and grids.

Like all filters, you’ll need to monitor the tank’s pressure gauge so you know when it’s time to clean it. For DE filters, this will be when the gauge reads 8 to 10 PSI over it’s initial or “normal” reading.

DE powder is also required for the filter. This powder is hazardous if inhaled, so make sure you always wear a chemical mask when using it.

What you’ll need before starting:

  • A garden hose with spray nozzle
  • DE powder
  • Chemical mask
  • Chemical-resistant gloves 
  • DE filter cleaner
  • A five gallon bucket
  • Muriatic acid 
  • Safety goggles
  • A replacement O ring (backup)
  • A replacement manifold or filter grid (backup)

Step 1. Turn Off The Pump

You’ll need to start by turning off your pool pump.

This will cut off water flow to the filter tank, and allow you to use the multiport valve. Using this valve without turning off the pump can cause catastrophic damage so follow these steps carefully. 

Also, you should also take note of the current PSI level on the tank’s pressure gauge. It should drop by 8 to 10 PSI once the filter is cleaned out.

Step 2. Backwash

If you have a waste line plumbed into your pool system, this process will be pretty simple. 

If you don’t have a dedicated waste line, you’ll need to hook up a backwash hose to the filter’s “Waste” port, and run it to a safe place where you can dump waste water. 

This is usually a sewer or storm drain, but check with your town’s regulations so you aren’t illegally disposing of dirty pool water.

With the hose attached, turn the pump back on and let the filter backwash between 3 and 5 minutes.

Monitor the sight glass on the side of the multiport valve. When the water turns from cloudy to clear, you’ll know it’s time to turn off the pump, thereby stopping the backwash process.

Step 3. Rinse The Filter

With the pool pump now off, open the air relief valve on the filter tank, and remove the drain plug. This allows any remaining water inside the tank to drain.

Open the filter tank, remove the manifold, and take out each grid. Use a garden hose with a spray nozzle to hose down any built up debris on them. 

Once clean, you can rinse out the inside of the tank (water will escape through the drain plug). 

Step 4. Put It Back Together

Reconnect the grids and manifold and place it back inside the filtration tank. 

Inspect the tank’s O-ring for signs of deterioration. If it’s damaged, replace it. If it’s still usable, apply a coating of O-ring lubricant on it. 

Open the pool pump lid, and fill the strainer basket with water from the hose. Lubricate it’s O-ring (or replace it if need be), and put the lid back on. 

Release any excess air in the filter tank using the relief valve. 

Turn the pump back on and close the relief valve on the filter tank. Check that the PSI pressure on the tank has dropped back to it’s initial readout.

Step 5. Add DE Powder

Adding DE powder is done through the pool’s skimmer. Remember to wear chemically-resistant gloves and a chemical mask when using the powder.

Consult the manufacturer’s instructions for the correct dosage of DE powder, which is determined by the filter size.

DE Filters are available in 24, 36, 48, 60, and 72 square feet. The dose is usually calculated by dividing the square footage by 5.  For example, a 36 square foot filter would require 7.2, or in this case, 7 scoops of DE powder.

The powder should be mixed in a large bucket with water to create a slurry consistency and then poured directly into the skimmer. 

The pump will suck it into the pool system and the DE will stick to the filter grid as water passes through it. Continue running the system for at least 30 mins after adding DE powder.

Yearly Deep Clean

Over time, oils, stains, and mineral deposits will accumulate on the filter grids. To remove them, you’ll have to do a deep clean of the grids once a year.

For mineral deposits, soak the grids for several hours in a diluted solution of muriatic acid (5:1 ratio). Remember to be careful when handling muriatic acid, as it is hazardous to humans.

When it comes to oils and stains, there are multiple cleaning products for DE filters that can remove them from the grids. All you have to do is follow the instructions on the bottle.

The Pressure’s On!

A clean DE filter is vital to clean water, but recharging it doesn’t have to be a nuisance.

With the right attitude and using the above instructions, you’ll feel a sense of accomplishment by cleaning the filter yourself, and you’ll also save money from hiring a professional to do the job.

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