The most common type of filter you’ll come across in a pump room of a swimming pool is a sand filter.

Most people aren’t aware of the amount of water that is lost while backwashing or how long they need to backwash their filters, nor where the water goes. The water is drained along with all the chemicals that were in your swimming pool.

This means that the amount of water that has been drained needs to be refilled back into the pool and rebalanced. Click here to learn about maintaining your pool.

There are various reasons why this is common practice. Sand filters are commonly found in any pool shops, displayed right by the window and since it’s the only type of filter that is displayed, few people consider whether there's an alternative to sand filters, which leads to it being the standard way to filter a swimming pool.

What are the positives and negatives of using sand filters?

Positives:

Easy installation
Easy to backwash
Removes down to 20-40 micron-sized dirt and debris
Sand filters hold longer than cartridge filters
Sand is cheaper to replace

Negatives:

Backwashing lowers pool water
Requires frequent cleaning
Does not catch small particles like a cartridge filter
Constantly backwashing causes imbalance in your pool chemistry
Lower filtration area compared to a cartridge filter
Takes up a lot of space compared to a cartridge filter
Sand filter can break while taking out sand from the filter using the wrong equipment

What is a cartridge filter?

Unlike a sand filter, water passes through a cartridge made of a special material which traps particles on the surface. Cartridge filters are becoming increasingly popular since they are smaller in size, extremely energy efficient and save water. A cartridge filter doesn't require backwashing therefore water doesn’t get wasted.

What are the positives and negatives of the cartridge filter?

Positives:

Easy to install
Filters water down to 10 micron-sized dirt
Simple maintenance
No backwashing required
More energy efficient than sand filters
Larger surface area to clean out dirt particles
Does not cause water chemistry imbalance
Saves water
Doesn't take up as much space as a sand filter

Negatives:

Cartridge filters need to be replaced every 2 to 3 years, depending on how it’s used/cleaned
Needs to be taken out and washed
A cartridge costs more to replace compared to sand

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