Can You Add DE to a Cartridge Filter? (Answered!)

You read on our blog that you can use diatomaceous earth or DE in a sand filter. You have a cartridge filter for your swimming pool rather than a sand filter. You’re curious whether you can add DE to your cartridge filter. Can you?

You shouldn’t add DE to a cartridge filter. The diatomaceous earth can clog up a cartridge filter, making filtering ineffective and raising the pressure too high. It is also very hard to clean or remove DE from a cartridge filter.

Ahead, we’ll talk further about why you shouldn’t use DE in a cartridge filter, whether you can make a cartridge filter into a DE filter, and how to keep your water clean with just a cart filter. Make sure you keep reading!

Pool Cartridge Filter

The Dangers of Adding DE to a Cartridge Filter

Going back to what we said in the intro, DE is not designed for cartridge filters.

A cartridge filter features a pleated cloth filter made of spun polyester.  When pool water passes through the pleats, the polyester will hold onto the particles, but only between five and 25 microns. That’s still better than a sand filter’s particle-trapping capacity, which is 20 to 40 microns.

So what happens if you mix DE and a cartridge filter in your swimming pool? Here are the risks you could incur.

More Frequent Filter Replacements

When used properly, a cartridge filter is only supposed to need replacing maybe every 1-3 years. There is no set time actually – it’s based on wear and tear.

Each time you clean your cartridge filter, you’re reducing its effectiveness one cleaning at a time. The filter pleats deteriorate and they tend to clog up to a point that even cleaning it won’t fix it. Eventually rendering it useless.

You’re only supposed to clean a cartridge filter twice per year to get the maximum life out of it. Yet pool owners who have added DE to a cartridge filter have found they have to clean their filter a lot more.

The woven polyester and diatomaceous earth don’t play well together. The DE gets stuck in the pleats, causing you to have to spend hours removing the stuff. In doing so, you’re killing your cartridge filter more and more.

You won’t get nearly as many years out of the filter as you should. Even though cartridge filters aren’t the most expensive type of pool filter, any unnecessary replacement is a hit on your wallet.

Cloudy Water

Diatomaceous earth itself is between three and five microns. We established above that a cartridge filter can only filter the water down to five and 25 microns. Thus, DE might be smaller than what a cart filter can reasonably catch.

What do you think happens in a scenario like that? The diatomaceous earth that doesn’t get caught in the cartridge filter will now enter your pool.

With DE floating throughout your pool, the water is going to become more and more opaque. That cloudy quality can be hard to eliminate and you may need a flocculant to remove it. That can be a time-consuming job!

HTH 67029 Drop Out Flocculant Swimming Pool Cleaner, 1 qt

Pump Breakage

Here’s yet another byproduct of DE getting in your pool. Your swimming pool circulatory pressure will begin to increase if the DE has clogged your filter. And with increased pressure, the pump has to work that much harder to push the water through the filter. Which in turn can lead to pump failure.

Respiratory Health Harm

A little bit of DE is quite a big deal. The above dangers aside, swimming in a pool with DE lingering about can be bad for your health and that of your family. Diatomaceous earth is known to be hazardous to respiratory health should you ingest it.

In fact, it’s been classified by some government departments as a carcinogen.

Tips for Clearing Water Without Adding DE to a Cartridge Filter

When cloudy water leaves you feeling woeful, the solution is not to put DE in your pool’s cartridge filter. Instead, you can use these methods.

Balance the pH and Chlorine Levels

It’s time to pull out your pool testing kit, as you need to determine the levels of chlorine in the water as well as the pool’s pH.

TAYLOR TECHNOLOGIES INC K-2006 TEST KIT COMP CHLORINE FAS-DPD

The desired pH range for your pool is 7.2 to 7.6. If your levels are below that and you’d like to increase your pH, add:

  • baking soda or;
  • soda ash

To lower the pH use:

  • muriatic acid or;
  • sodium bisulfate

Should your pool have well under the recommended amount of chlorine, then you’ll want to replenish that as well.

Use a Stabilizer

Next, we recommend making sure you have the appropriate levels (30-50 ppm) of pool conditioner or chlorine stabilizer.

Pool Mate 1-2604B Swimming Pool Stabilizer and Conditioner, 4-Pounds

Pull Quote: Stabilizer (CYA) should be 30-50 ppm.

A stabilizer helps the chlorine in your pool last even longer. Your pool could certainly use the extra help right now, so use the stabilizer according to the manufacturer’s instructions.

Clean Your Filter

Although cleaning your cartridge filter will reduce its effectiveness, it’s still inevitable that you’ll have to clean it. Hosing off the cartridges is the first step. And for a deep clean you can soak them in diluted muriatic acid.

That will in turn help your pool look crystal clear again.

We have a full guide detailing how to clean a cartridge filter in our article How to Clean Pool Cartridge Filter (Using Muriatic Acid).

Can You Convert a Cartridge Filter to a DE Filter?

If you read our blog post comparing sand filters, cartridge filters, and diatomaceous earth or DE filters for swimming pools, then you may recall how DE filters can filter the water down to the most microscopic particles.

The particle filtering size of a DE filter is between two and three microns, which is truly extraordinary. It’s why pools with DE filters can look cleaner.

And if you value that, perhaps you’d ultimately want a DE filter for your pool. However, they tend to be more expensive and take much more maintenance than sand or cartridge filters.

To save some money, you had the idea of converting a cartridge filter to a DE filter. Is this possible?

No, you can’t make a cartridge filter into a DE filter. Adding DE to a cartridge filter will just clog it up. DE filters are designed for DE.

Interestingly, what some pool owners do is take their DE filters and begin using cartridge filters on them instead. This guide from pool company Inyo Pools shows you how complete with pictures.

If DE filters can filter water particles down to the finest degree, you may wonder why anyone would abandon such an efficient filter. Well, it’s because that efficiency comes at a price.

DE filters, besides being the most expensive of the three pool filter types, are also the most time-consuming and difficult to maintain.

You frequently have to backwash the filter, add more diatomaceous earth when the levels are low, and then clean the filter grids at least two times per year if not more often. It’s a lot of work to have to commit to!

That said, taking a very expensive pool filter like a DE filter and then making it into a cartridge filter, while doable, does feel like a bad use of the money you spent. You could have just bought a cartridge filter in the first place!

Conclusion

Diatomaceous earth or DE is valuable in a DE filter, and it can even be useful in a sand filter. However, in a cartridge filter, DE can muddy things up. You’ll end up with a cloudy pool that could put a strain on the pump and the skimmer.

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