Can a Pool Sand Filter be too Big?

Your pool requires a good amount of equipment to keep it going and to maintain its cleanliness. After all, no one wants to swim in a swamp and your pool’s sand filter is one of the biggest players in this equation, but how does its size affect the filtration capacity? 

A pool sand filter cannot be too big. In fact, the larger cartridge provides better filtration leading to a cleaner pool through decreased maintenance, less stress on the motor, and a longer filter life. Avoid getting a sand filter that is too small as this can be catastrophic for your pool.

Bigger isn’t always better, but for your pool, if you have a larger-than-life sand filter, the better your pool is going to fare when it comes to staying clean. This is one of those instances where the bigger model is going to give you more bang for your buck. Continue reading to figure out why an oversized filter is not an issue, the advantages to having a large pool sand filter, and the disadvantages of a sand filter that is too small for your pool’s size.

Will a Big Pool Sand Filter Cause Problems for Your Pool? 

The purpose of a pool filter is to go through the entirety of your pool’s water within a certain period of time and filter out all the bacteria and debris that should not exist within your water. Because of the serious work that pool filtration systems do, there is such a thing as a “flow rate.” Flow rates are important because with each individual filter there is a maximum working pressure, filtration rate, and filter media requirement. 

A big pool sand filter should not cause any problems for your pool. Contrarily, a larger pool sand filter will allow for an increased maximum flow rate thus increasing the capacity for maintaining a clean pool. Check the volume of your pool to determine the appropriate sized sand filter you should use.

There is a point where too much debris is too much for your pool’s sand filter which can be translated to the “maximum flow rate.” But if you were to look on the filter that you currently have, there is no way you would ever find anything stating the “minimum flow rate.” That is because such a thing does not exist! As it turns out, your pool sand filter does not care how small your pool is, just as long as it has water to clean, it’s happy! 

For you, this means that your sand filter is still going to get that water just as squeaky clean as if it were a more equal size with your pool’s water volume. If you have found yourself needing a smaller pool and do not want to downsize your sand filter or if you ordered one that is way bigger than you expected, fret not. That sand filter is going to do the same job as any other sized filter and you will not have to worry at all about maxing out the flow rate!

Are There Advantages to Having an Oversized Sand Filter? 

You now know that it is no problem to have a sand filter that is too big for your pool. It is still going to function properly and will not discriminate against the puny amounts of water being sent through it when it is capable of so much more. 

Even though we know that the sand filter will function just fine, could there actually be any advantages to having an oversized filter? Interestingly, a pool sand filter that is too big can be advantageous to your pool in that it requires less maintenance, less stress on the motor, and has a longer filter life.

Let’s take a closer look. 

Less Maintenance 

A larger filter means that you have much more room for all of that pool gunk to go through. For you, this means much less maintenance than you would have had with a filtration system more matched with the size of your pool. There is more area for dirt to disperse through and therefore more area for water to also make its way through. This process does not wear on your filtration system as much because it has more room to get down and dirty in. 

This is also a huge win when it comes to helping to maintain water pressure. There is nothing worse than looking down at your main pool filter and realize that everything going in the filter is coming right back out. Once you see the issue, you have to backwash and take the time to get pressure up and going again. It is dreadful and no one wants to stop the pool party for it. With more area to take in dirt, pressure is better sustained and your time is not interrupted. 

Less Stress on the Motor 

Your filtration system is going to be doing less work, but so is your motor if you size up on your sand filter. The whole purpose of your motor is to get water in and get water out. This is no easy task and takes a ton of power to get the job done well and efficiently. If you have a filter that is completely backlogged due to either poor maintenance or bad sizing, the motor is the one that is going to pay the most. 

A larger filter means a larger motor and a larger motor means a less stressed piece of equipment overall, a great flow rate for your filter, and less worry for you. This will help to extend the life of your motor due to the lack of stress that it is experiencing and result in a more consistently clean pool. Just as the filtration being larger helps to keep you from having to maintain it constantly, a fine working motor will also allow you to kick your feet up. 

Longer Filter Life 

Guess what, the sand in a sand filter does in fact have to be changed. I know, this is devastating news to those of you that thought this type of filtration system was a one and done type of deal, but it, unfortunately, is not. Every five to seven years the sand in your sand filter has to be changed. Why? Because after years of hard work the sand begins to wear out and degrades to dull particles which keep it from properly capturing contaminates. 

However, if you have an oversized sand filter that has more room to trap those contaminants, you have a much greater chance at extending the amount of time in between sand changes, and trust me, it is not a fun job. Overall, there is going to be less stress on the sand filter due to a good disbursement of water flow and dirt helps to give the sand a bit of zen. The low stress that happens will extend the sand’s life and leave you more time in between changes. 

What Happens if Your Pool Sand Filter is too Small?

If you want the big sand filter, the one with flashy chrome pieces, a giant water capacity, and incomprehensible flow rates then you go right ahead and fulfill those filter dreams! No one is going to stop you because, guess what, there is no such thing as a sand filter that is too big. However, if you have a pool that can hold half of the Atlantic in it but want a sand filter that is only capable of filtering something more like the pond in your backyard, you will be sorry. 

A filter that is too small for your pool and pump size cannot handle the pressure that they force onto its tiny little surface. Malfunctions will occur and outside of this, cleaning your filter will have to become a very regular practice. If your pump is pushing large amounts of water into a filter that is too small, it is either going to get so clogged that it no longer works, or you will be left with a busted pipe. 

I have gone on and on about how great it is for your pool and for your filter to have more room when it comes to disbursement, less strain, and overall cleanliness. But what happens when you do not give your filter enough room to get through your pool’s water without strain? Disaster. 

For those of you with a sand filter, changing the filter as frequently as you would have to if it were too small can easily bring in visions of horror stories. No one wants that to be a regular occurrence, so always avoid going for the smaller sized filter. 

If you are someone who does not like the look of a sand filter sitting in your backyard, I completely understand! They are big, they are eyesores, and they do not go well with your flower beds. If you do not like how they look, consider putting in a bit of landscaping around them to keep them under wraps or add a fence to get it out of your line of sight. A bit of TLC and you can have the pool, filter, and yard of your dreams!

Jed Arnold

Jed spent every year from the ages of 15 - 22 as a Lifeguard (Red Cross) and ages of 17 - 22 as a Certified Pool Operator (CPO). Between working for over a dozen facilities and owning a pool, he carries over a decade of pool experience.

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