Your hot tub filter is critical to your hot tub’s health. Nothing is more important. A filter’s job is to take dirty and contaminated water from the spa into its system. Once the water enters it is then cleaned, and then injected back out into the spa for further use. This is important because you need to make sure the water you swim in is clean and free of any debris or any other potentially harmful items.
When looking for hot tub filters, there are 3 distinct types of filters; cartridge filters, diatomaceous (D.E.) filters, and sand filters. In the next three sections we will detail how each of them works. This should provide clarity on what filter is the “best” for your needs.
Hot tub filters come in 3 main styles:
Sand Filters are a low-priced filter with little need for maintenance. These are the least effective at filtering. Sand Filters are very useful for larger hot tubs because they don’t often become clogged. However, this type of filter can slowly erode and become less effective as pressure builds in the filter and time passes. A sand filter typically lasts 5-7 years.
Cartridge filters are a medium-priced filter. They come with higher efficiency rating and clean better than sand filters. They are just as easy to maintain as a sand filter but is more effective in practice. A cartridge filter typically only lasts 3-5 years before needing to be replaced.
A D.E. or diatomaceous earth filter is the best, but also most expensive type of filter with the most maintenance. Like a sand filter, The D.E. filter needs to be backwashed. However, a D.E. filter always needs fresh DE powder added. The hardest working and best for overall water cleanliness (filters smallest particles). A D.E. filter does not need to be replaced very often, however the internal grid will need to be replaced every 2-3 years. These filters carry some health risks as the powder can cause eye irritation or lung damage if you are exposed.
Each of these offers distinct advantages and disadvantages that you need to be aware of before you can make an informed decision. Below are the differentiating characteristics that match each type of filter:
Being the cheapest hot tub filter for consumers to purchase, sand filters do the job. Actually, they do exceptionally well given their reasonable price point. This cost is also paired with a low need for maintenance from the user. Gravity does a lot of the job for you, pulling the water from skimmers through the sand and filtering the water in a streamlined manner. This process almost entirely operates itself. These filters typically last 5-7 years depending on how much work is required to be done.
Sand filters do require to be on top of your water chemistry game. Since they are the least efficient of the filters, sand filters only can capture and clean larger particles (20 microns or larger). This means that keeping your hot tub well balanced with chemicals is key to killing the smaller particles that may be lurking in your water. Your sand filter can handle the large debris, but you will be required to put in extra work to reach the cleanliness levels of the two other types of filters.
Cartridge filters are a step up from sand filters both in terms of expense and efficiency They represent a middle ground for consumers. This filter is not too expensive, nor too weak in terms of filter power. Cartridge filters do require more maintenance than a sand filter. Cartridge filters rely on a plastic cylinder that is surrounded by a polyester filter. The water flows in through one end of the cylinder, and particles of as small as 10 microns (half the size of the capabilities of a sand filter) are captured and stored in the tank. The newly cleaned water is then spewed through the “out” end of the cylinder and filtered back into the spa. Filters typically last for 3-5 years, depending on how much work is required to be done.
These cartridge hot tub filters require constant cleaning. This means that you need to be able to physically remove them and rinse them off in order for them to be the most effective. Also, occasionally these filters will need to be sprayed with filter cleaner. This chemical mix is necessary to keep your filter clean and running smoothly.
Often considered the “top dog” in the filter industry, diatomaceous filters are the most expensive of the three options. They also clean water the deepest. This shows in the fact that D.E. filters can clean particles as small as 5 microns (two times smaller than cartridge filters, 4 times smaller than sand filters). You can rest assured that your water will be clean and safe for everyone using it. D.E. filters are so effective because they use an internal grid covered in white powder made from diatoms (remains of tiny aquatic organisms) that help clean and filter the water.
This powder is used as a sort of “pest control” in your water, and when used with the filter can almost completely eliminate all waste from the water, giving you peace of mind. D.E. filters also do not need to be fully replaced very often, but the grid inside of the filter will require a replacement every 2-3 years. For more on maintaining a DE filter, see video here.
D.E. filters do have some notable issues. Along with the high price mentioned previously, there will be a need for constant upkeep of the filter. Along with this, the use of these filters can be limited in your locale based on regulations based on the environmental and waste risks associated with this filter. The diatom powder can be hazardous, and this means that not only are there possible environmental damage associated with this filter. The powder can be dangerous when exposed directly long-term to humans, but is not considered dangerous to those swimming. This means that you must be careful when handling the powder and take precautions such as wearing chemical masks and gloves to prevent any possible accidents.
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