Pool Filters 101

Last Updated: March 20 2016

A filter is the most important piece of equipment you need for your pool, so it’s important to get it right. In this blog post, we will be discussing three different types of pool filters – and some tips on how to maintain them.

Cartridge filters

The first type of filter we’ll be discussing is the Cartridge filter. Cartridge filters are cylinders of porous accordion pleated material capped on either end with plastic. The water in your pool is pumped through this material and oil, dirt and other particles become trapped in the pleats. Cartridge filters are very effective at removing dirt and debris from your pool and are easy to maintain.

The lifespan of a cartridge filter depends entirely on the care you take with it. You need to clean it regularly by hosing it down and (preferably) also soaking it in cartridge cleaner overnight. You must also never use a stiff brush or high pressure hose on your cartridge filter or you can create tears in it.

Some signs that your cartridge filter will need replacing are:

1. Visible tears – if the polyester fabric has any tears in it, it will obviously no longer be good at filtering small particles out of your pool water

2. Flattening of pleats and frayed edges – Yet another indicator that the fabric within your filter is no longer effective at filtering

3. Damage to plastic caps or bands – The plastic components of your filter are integral to its structure – replace the cartridge if any of these components begins to crack

4. Change in water pressure – Namely, higher water pressure than normal can indicate a clogged filter which will need replacing

Sand Filters

Sand filters use gravity to filter pool water through special (silica) sand which captures the debris in your pool and then deposits the clean water back into your pool from the bottom of the filter. Sand filtration systems are the oldest type used and are quite effective, though not as effective as a cartridge filter.

Over time, the rough, finely ground silica sand grains within your filtration system will wear down from the constant water flow and become smooth and less efficient at filtering pool water. Your filtration system will need to be replaced every five or so years.

Your sand filtration system will require regular backwashing to float all of the particles up to the top of the filter and out of it. This can use a lot of water and care has to be taken to ensure you use as little as possible. Keep an eye on the water in the sight glass – once it is clear, stop backwashing.

The easiest way to know when your sand filter needs backwashing is higher pressure

Diatomaceous Earth Filters

Diatomaceous Earth (DE) is, rather fascinatingly, comprised of powdered fossilised microscopic organisms. This powder coats a grid element within the filter and the pressure from your pump forces the pool water through it, filtering it more effectively than either of the other two systems mentioned here.

A DE filter is cleaned in the same way as a sand filter – backwashing. However, when you have backwashed and the water runs clear, more DE media must be added to your filtration system in order to keep the grid within coated and your filtration system effective. A good maintenance practice to keep is thoroughly cleaning your DE filter at least once a year. You will need to turn your pump off, drain the filter, remove the grid element housed within and hose it down. Soak it in filter cleaning solution overnight for a perfect clean.

As with the previous two filtration systems – high water pressure means you need to backwash your filter.

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