Sand vs Cartridge filters

If you are confused about which pool filter is the best for your pool, then you are not alone. There are a huge range of filter choices on the market, each promising to make your pool cleaner than the last. In this article we aim to demystify filter to help you make the best choice for your pool type and lifestyle.

How does a sand filter work?

Sand filters work by having water flow into the multiport valve (MPV). The MPV will then dictate whether the water runs through the sand and then whether it flows out the waste line or continues through the pool’s circulation line. Assuming the filter is just operating on the normal “Filter” mode, the water will flow down through the filter media, with the media catching any dirt/dust & other pollutants whilst allowing the now cleaned water through to the bottom where it flows into the laterals and back into your pool. If the filter is being backwashed, this process is reversed with water shooting up from the bottom of the filter and carrying all the pollutants trapped in the filter with it, where it is then flushed out of the system through the waste line.

Benefits of a sand filter

• Last longer than cartridge filters.
• Have to be cleaned a lot less frequently than the cartridge filter usually does.
• When they do have to be cleaned, are a lot easier and less labour intensive to clean.
• Cheaper in the long run.
• Tend to have fewer issues.

Downside of a sand filter

• Much higher upfront cost than a cartridge filter.
• More work to install initially than a cartridge filter.
• In salt water pools, have to be aware of where the cell is installed due to potential chlorine gas trap issues.
• Harder and more expensive to fix than a cartridge filter when something breaks.

How does a Cartridge filter work?

Cartridge filters are very simple in their design. Water enters the cartridge filter through the inlet, washing flowing through the actual filter cartridge. The filter cartridge is made of folded filter paper, very similar to a cheap coffee filter. As the water flows through the filter cartridge, the filter paper picks up any impurities or pollutants whilst allowing the clean water through.

Benefits of a Cartridge filter

• Lower upfront cost vs a Sand Filter.
• Easier to install than a sand filter.
• Easier to fix if something breaks than a sand filter.
• Technically does a better job of filtering (very minimal practical effect for pools though).

The downside of a Cartridge filter

• More expensive long term than a sand filter.
• Have to be cleaned far more regularly than sand filters.
• Are a lot more work to clean than sand filers.
• Tend to break easier than sand filters.