When to Change the Sand in the Pool Filter (And the Risks)

Is your pool water cloudy? You might have assumed your filter isn’t working at 100 percent efficiency. You figure that changing the pool filter sand is the best fix, but it likely isn’t. That’s not to say that the time won’t inevitably come when you should replace your pool filter sand. How often will that be?

The sand in your pool filter needs replacing every three to five years, sometimes even longer if your pool remains in relatively good condition when it’s open. If you run your pool filter often all year and have a heavy bather load, the sand may need replacing sooner than three years.

If you have questions about pool filter sand, don’t worry, as we’ve got answers. Ahead, we’ll talk further about the lifespan of pool filter sand as well as when to replace yours, which sand to use, and why you shouldn’t change out the sand too often.

You won’t want to miss it!

How Long Does Pool Sand Last?

Pool filter sand is not like the stuff you find at the beach, nor is it the sand that fills your children’s turtle-shaped plastic sandbox. The latter is play sand, and it has bigger particles and different ingredients.

Pool filter sand is usually #20 silica sand that’s sourced from ground quartz. It has a tough base, so how long will your pool filter sand last? Well, that depends.

First of all, older pool sand filters are filter better than brand-new sand. It’s best not to replace it unless you need to.

If you’re someone who keeps your pool open all year long because you live in a hot climate, then your pool filter doesn’t get much of a break. This causes the sand to break down faster, maybe in two or three years or less.

Perhaps your pool is only open from late Spring to early Fall or so. The rest of the year, the pool is closed and the filter is off. You can get more time out of the sand, anywhere from three to five years, sometimes as long as six years or more.

What happens to the sand as it breaks down over time? The normally jagged, sharp edges of the #20 silica sand become rounded and smooth, losing their effectiveness.

Filter Sand
Filter Sand

How to Tell If Your Pool Sand Needs Replacing

We’re not asking you to study each grain of sand in your pool filter to determine when the sand needs to go. That would be ludicrous! Instead, here are some telltale signs that your pool filter sand is past its useful life.

The Pool Always Looks Cloudy

You painstakingly clean your pool and measure the chemicals, yet it still looks cloudy. You’re not sure what else to do at this point.

backyard swimming pool with cloudy water
Cloudy swimming pool.

Although pinning the blame on your pool filter sand might make you feel better, it’s not going to make your pool magically less cloudy. More than likely, your issue isn’t with your pool filter at all, we’d bet.

There are plenty of reasons your pool could be cloudy, many of which we touched on here: How to Fix a Cloudy Pool

Chemicals such as calcium hypochlorite or calcium carbonate could lead to murky water quality. So too can dust, leaf mold, pollen, or algae, not to mention all the human sources. You know, like bodily fluids (sorry, but it’s true), body oils, and sunscreen oils

We’d recommend chemically testing your pool water composition to rule out these other causes. If the water is still cloudy even then, then it might be an internal pool filter problem. The sand in the filter would have to be very fine to cause any issues with water cloudiness.

Backwashing Sessions Are Shorter

The pool filter sand can get greasy or dirty, which will cause you to have to replace it sometimes sooner than even three years. Again, we’re not saying you’ll have to study each grain of sand in the filter to know.

Shows what backwashing is and how it works. The image on the left demonstrates regular filtering, the image on the right shows what happens when you backwash your pool.
The image on the left shows regular filtering, and on the right side, backwashing.

Instead, the next time your pool runs its backwashing cycle, keep an eye on how long the cycle lasts. It probably won’t be as long as it usually is. How long???

Channeling

Channeling is when the water enters the filter but makes its own path through the sand without having been filtered well, if at all.

In some severe instances of channeling, the water can go through either edge of the sand filter tank and skip the sand altogether. Your pool water will be dirty in no time.

You can see if this is a problem by opening up the pool filter. The sand will have ridges in it, often around the edges.

Channeling is usually caused by having a pool pump that is too big for the filter or by using some pool chemicals. Chemicals like clarifiers can contribute.

If your sand is rather new or the pool season is just about over, you can try:

  • Opening the filter and smoothing the sand out
  • Backwashing the filter
  • Using a sand filter cleaner (enzyme and phosphate remover)
  • Replacing the sand

Try this Before Changing Sand

Before you rush out and change your sand, you can try using a sand filter cleaner. This will remove any oils, residues and caked-up chemicals in the filter.

Sand Filter Cleaner

POOLIFE Backwash Filter Cleaner
Sand Filter Cleaner

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Recommended Pool Filter Sand

Since it’s inevitable that you’ll have to replace the sand in your pool filter at some point, we thought we’d take this section to recommend you two of our preferred brands of sand.

FairmountSantrol AquaQuartz

FairmountSantrol AquaQuartz Filter Sand
FairmountSantrol AquaQuartz Sand

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First on our list is AquaQuartz by FairmountSantrol. This #20 silica sand is premium quality and odorless. From algae to hair, dust, dirt, oils, leaves, and insects in your pool, FairmountSantrol’s AquaQuartz sand is built to remove it.

FairmountSantrol only uses natural sand for AquaQuartz so backwashing will be easy. The sand won’t solidify so channeling isn’t a concern either. You can order AquaQuartz pool filter sand in 50-pound bags.

Zeo, Inc. ZeoSand

ZeoSand
ZeoSand

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An Amazon’s Choice product and one of our top picks as well, ZeoSand is a natural pool filter sand that cuts down on the volume but not the efficiency. You only need 50 pounds of ZeoSand to make up for 100 pounds of pool sand from other manufacturers.

ZeoSand is designed for capturing particles and dirt so your pool looks cleaner. Zeo, Inc.–the makers of ZeoSand–says one bag of ZeoSand is good for five years.

The Risks of Changing the Sand

We want to reiterate that changing your pool filter’s sand is something that will surely happen at least several times over the life of the pool but you shouldn’t rush to do it.

If you find yourself having to replace the sand too often though, that’s indicative of an issue with your filter or another component of your swimming pool.

Here are the risks you face each time you change the pool sand.

Broken Laterals

If you’re not familiar with your pool’s laterals, allow us to familiarize you now. Laterals are attached to a central pipe in a pattern like a wheel spoke. The lateral has sieve-like holes for water to travel but sand to remain trapped.

Internals of a pool sand filter
The stand pipe and laterals of sand filter can break when changing sand in a filter.

When replacing the sand in an old pool filter you run the risk of damaging the laterals. As the laterals age, they can become delicate and brittle. Any additional movement can cause them to break.

To replace a lateral, you have to first access the sand bed and remove the sand, but you won’t have to detach the sand filter at least.

Broken Standpipe

It’d be nice if a damaged lateral pipe was your only potential headache when replacing pool filter sand, but that’s not true. Another issue you can have is with the standpipe, which is the vertical pipe inside the filter. The purpose of the standpipe is to move the water from between the laterals and the inlet/outlet of the filter.

Since the standpipe and laterals are in proximity, if one goes, the other usually goes with it.

Broken Multiport Valve or Seals

Your swimming pool’s multiport valve could also be in danger by replacing the pool filter sand. The multiport valve earns that name due to the number of ports within the valve. The ports can push water in various directions according to how you control the multiport valve’s lever.

It’s the big valve, usually on top of your filter that you select the different filter settings with.

When you open up anything aged, you run the risk of damaging it if it’s hanging on by a thread.

Why You Shouldn’t Change Pool Sand Too Often

In addition to the above risks, here are several more reasons to refrain from changing your pool filter sand more than you have to.

Older Sand Filters Better

There’s something about older sand that filters your pool more efficiently provided the sand grains haven’t become too rounded. As the sand ages, it get’s a little bit smaller. Since it’s smaller, it will trap smaller particles – which means it cleans better.

You’ll likely be happier with old sand than the new stuff, until it ages that is.

It’s Messy

Although pool filter sand isn’t play sand, at the end of the day, all sand behaves the same. The particles are small so they can quickly make a mess all over your pool deck or your clothing. Sand will inevitably get into your shoes, and then good luck ever getting it out again.

It’s a mess. Plus carrying 50-100lbs of new sand and removing 50-100lbs of old sand isn’t fun.

Maintaining your pool can be hard enough, so whatever makes it more difficult is not a task you want to commit to all that often. That includes replacing pool filter sand.

Sand Can Leak in the Pool

We saved the best reason for last. If you’re not yet dissuaded from changing pool sand too often, keep in mind that it can leak in places beyond your shoes and your pool deck. The sand can also get in the pool itself.

It’s usually caused by broken laterals or a broken standpipe. As mentioned, these parts are easy to damage and you may not even notice you’ve damaged them until you turn the filter back on – which would be very annoying!

Sand is supposed to be in the ocean, not your swimming pool! Now you have to get it out before it can scratch up the liner and cause other damage. Removal will entail moving the sand with your pool brush and then using your multiport filter to suck up the sand.

Conclusion

Pool filter sand lasts between three and five years, sometimes more if yours is well cared for. We want to stress again that while pool filter sand replacements are inevitable, they’re not something you want to do any more often than necessary. You can wear down crucial pool parts, and your pool risks getting sand in it. By taking care of your sand today, it will last longer later!

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