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Everything You Need to Know About Your Pool's Sand Filter

Everything You Need to Know About Your Pool's Sand Filter

Sand filters are widely used across the swimming pool and hot tub industry. This is because sand filters are simple, durable, and effective. However, as with all things pool and spa, sand filters require some care and maintenance. This article will provide pool and hot tub owners a comprehensive overview of the sand filter. Let's jump right is!

What Is a Sand Filter

A sand filter, sometimes called a sand water filter is a device that uses fine sand to filter water. Sand filtration is perfect for a recirculating system. A recirculating system filters waste out of water and returns filtered water to the main reservoir, in this case the swimming pool or hot tub. 

Sand filters also have many industrial applications. For example, sand filter technology is used for pre-filtration, irrigation, rinse water processing, and basin water filtration. In fact, our drinking water that comes from aquifers is rain that is filtered by the rocks and sand in the crust above the aquifer. 

How Sand Filters Work

sand filter

Let's look at the aquifer example as a model for the sand filter. As rain water seeps onto the ground, it is filtered by the sand and rocks in the soil profile as it makes its way down to the aquifer. The sand filter uses the same model. When your filter is set in filter mode, your pool water will enter at the top of the unit through the inlet valve. This is the water that has just come through your skimmer baskets and pump strainer. The water drains from top to bottom through the sand collection at the bottom of the unit. At this point the water meets your pumps lateral assembly. The filtered water re-enters the circulatory system through the lateral assembly and into the outlet line. The filtered water is then returned to the pool. 

The sand in the sand filter removes the waste from the water. But wait a minute, doesn't that mean that the sand will get really dirty? It does. This is where some of the maintenance comes in. 

Maintenance of a Sand Filter

Over time the sand in your sand filter will become polluted. The dirtier it is the less efficient it becomes. This means you have to either clean it or change it. Cleaning your sand is called backwashing the filter. Your filter will need to be backwashed periodically based on the use of the pool. Heavy pool use required more frequent backwashing. 

Backwashing Your Sand Filter 

backwash setting on sand filter

Backwashing is exactly what it sounds like. The flow is reversed sending water back across the sand. This action removes debris, dirt, organic solids, algae, oils, hair, pollen, tiny twigs, insect parts and any other crazy stuff that makes it past your skimmers and strainers. This "waste" water exits the pump the waste outlet. 

Your sand filter should have a pressure gauge. Hopefully yours is working! Many of these gauges will be colored to indicate when you should backwash the system. If not, one rule of thumb in the business is to backwash if your read 10psi over your starting level. I like to backwash my system at the end of every pool season. 

Replacing the Sand in Your Sand Filter

Every now and then you will need to replace the sand in your filter. I have heard estimates anywhere from every 2 to 7 years. Some of this range depends on how much use the pool gets. every 3 to 4 years is probably a safe cycle for your sand filter. If you start to notice that your pressure is indicating backwash more frequently, it's probably a good idea to change your sand. 

Advantages and Disadvantages of a Sand Filter


Sand filters are great. The work well with above-ground pool, in-ground pools, indoor and outdoor hot tubs. They are also compatible with salt pools and swim-spas. You can find sand filters in a variety of sizes suitable for small and large pools. 

Sand filters are low-maintenance and easy to learn. This is nice because you don't have to put in a service call just to backwash your filter or even change your sand if you have a little spare time. 

Maybe best of all, sand filters are cheap. They're kind of like older American cars, they're cheap to repair or rebuild. Parts for sand filters are also very reasonable. 

Over all sand filters are inexpensive, easy to maintain, compatible with many systems, efficient, effective, and very durable. If you have a pool or hot tub with a sand filter, your lucky. If you are thinking about a sand filter, it's a good idea. And, if you're shopping for a sand filter, check out our selection of filters and pumps.  

I hope you enjoyed this article!

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