Sand and Cartridge Filters - Which One Do I Need?

Your pool filter is one of the most important parts of your pool. It works in conjunction with your pump to keep your water clean and free of debris. Most places in Canada contain by-laws on how often fresh water has to circulate through public pools, in order to maintain the perfect level of cleanliness. So it’s safe to say, that the filtration system you choose for your pool is pretty important.

This guide focuses on two of the most common types, the sand filter and the cartridge filter. Both do excellent jobs of keeping your pool clean, each with a different method, and each with their share of pros and cons.

What’s the Difference Between Sand Filters and Cartridge Filters?

Sand Filters

The way a sand filter works is it uses specially graded silica, usually 45mm - 55mm in size, to trap the debris that gets forced into the filter with the pump. The sand filter is considered one of the lowest maintenance pool filters you can choose since, if maintained correctly, it can go up to 10 years without needing to be changed. However, that’s a best case scenario. Best practices state you should be changing the sand in your filter once every five to eight years.

Regular Backwashing is Required

Just because the sand doesn’t need to be replaced very often, doesn’t mean the sand filter is completely maintenance free. Sand filters need regular backwashing, where the water is redirected to flow backwards through the filter, cleaning out the dirt.

There are two different types of backwashing mechanisms, a push-pull valve (also called a slide valve), or a multi-port valve. Regardless of the type of valve you have on your sand filter, always remember to turn off the pump motor before backwashing.

When you’re done backwashing ensure you read the pressure gauge. When the pressure gauge reads 8 to 10lbs after the last time you backwashed then it’s time to backwash the filter again.

How frequently should you backwash your sand filter? About once a month is normal. There are several possible reasons that may cause you to need to backwash more frequently than once a month:

• It’s possible that your filter has channels in it. Channels are large holes which can open up in the sand, this allows water and debris to flow straight through.
• If you have hard water flowing through your filter on a regular basis, parts of the sand may have calcified. These calcium deposits can cause the filter to be less effective.
• Your water may be out of balance, causing the sand to clump up.
• The wrong sized filter for your pool will cause problems. Filters that are too small won’t filter out debris properly.

Should You Use a Sand Filter?

Is a sand filter the right type of filter for your pool? Well, they:

• Are one of the most cost-effective pool filters
• Remove dirt as small as 20-40 microns
• Are easy to use
• Are low maintenance
• Don’t operate well if your pool has a low GPM (gallons per minute) capacity.

Cartridge Filters

Unlike a sand filter, with a cartridge filter water passes through a cartridge made of a special material which traps particles on the surface. Cartridge filters are becoming more and more popular since they are small in size, extremely energy efficient and save water. Unlike other filtration systems, cartridge filters don’t require backwashing, which means homeowners don’t waste the water and extra energy involved in backwashing.

The small size of cartridge filters allows them to be run on smaller pumps because they can run with a lower flow rate pump, which saves energy.

Unlike a sand filter, however, the maintenance for a cartridge filter is much higher. Since there’s no backwashing the filter has to be removed and manually cleaned. It’s best to take the filter out after you’re done using the pool for the day and let it soak overnight in a special cleaning solution. You can shave this time down, as long as it’s soaked for at least an hour, but for best results, the longer you keep it soaking the better.

Remember to hose off the filter before placing it to soak, this will help remove large debris such as leaves and any possible garbage that’s fallen into the pool. With the right conditions, you should only need to clean your cartridge filter a few times a season.

It’s almost impossible to fully clean a cartridge filter, in fact, over time it will become less and less clean, requiring you to replace it, usually every 18 to 24 months.

Purchasing the right type of cartridge filter can make a difference. When purchasing your cartridge filter, make sure you look for:

• Sharp filter pleats; The sharper the pleats, the larger the filtration area.

Should You Use a Cartridge Filter?

Is a cartridge filter the right type of filter for your pool? Well, they:

• Are more energy efficient than sand filters
• Reduce water consumption
• Don’t require backwashing, and therefore less plumbing is involved
• Are ideal for pools with low GPM capacity
• Have a larger surface area which screens out more particles than sand filters
• Are more time consuming to clean
• Are more expensive than sand filters
• Use cartridges which need to be replaced every 1 to 2 years

When choosing which pool filter is right for your pool, there are several things to take into account. While sand filters appear less expensive up front, they come with hidden costs since they require backwashing, which uses more water, energy and puts more wear and tear on your pump.

Cartridge filters are great for pools with low GPM capacity and use less water, space and energy, but they do require you replace the cartridge more frequently than the sand used in sand filters and cartridge filters also involve more maintenance.

Whether you want to get a sand filter, cartridge filter or are looking for replacement cartridges, Pool Supplies Canada offers the best brands at the lowest prices!