Swimming Pool Water Filtration

When you have a swimming pool you know that clean, clear water is a must! One of the things that can make or break your pool ownership experience is your swimming pool filtration system. When it comes to swimming pool filtration there is confusion and misconceptions about the types of filters available and the different options out there. On the market today there are three main categories when it comes to swimming pool filtration. They are sand filters, cartridge filters, and DE (diatomaceous earth). Here is a basic overview of each:


Sand Filter

Sand Filters:  As the name implies, in a Sand filter, sand is used as the filter media. The sand is placed in a large tank, when water enters it comes in through a diffuser. As the water travels through the tank, the grains of the sand trap debris. When the water passes through the sand it enters laterals which return it to the pool. Sand filters have the ability to filter out debris that is 40 microns in size or larger, anything under 40 microns will likely not be removed from the water by a sand filter.

When using a sand filter, as debris builds up in the sand and it becomes plugged, pressure will increase in your filter and then your water flow will drop. In order to clear the debris and allow filtration to keep going the filter needs to be “backwashed”. Backwashing is the process of running the filter in reverse and dumping the waste water. This process needs to be completed manually every couple of weeks to keep things moving properly.

Cartridge Filter

Cartridge Filter:  Cartridge filters contain a fabric media that is used to trap particles and debris when water passes through it. Cartridge filters have more area to filter debris than sand filters do, which can allow for better filtration and less maintenance. Cartridge filters can typically filter debris down to 20 microns in size. Filter cartridges only need to be removed and cleaned by spraying them off with a garden hose on average about twice every year, depending on usage.

D.E. Filter

DE Filters:  Diatomaceous earth consists of fossilized remains of diatoms, a type of hard-shelled algae. Grid filters are placed in the filter shell; DE is added to the pool skimmer, travels through the plumbing, into the filter and coats the grids. The coating of the DE on the grid then catches debris as it is passed through the filter. DE has the ability to filter down to 3 to 5 microns in size. For maintenance, a DE filter needs to be backwashed when the pressure reaches 10 units above your “clean” reading (usually ranges from 10-15). When backwashing, the flow of the water is reversed and the used DE that is coated on the filter is removed. After backwashing, new DE will need to be added again through the skimmer starting the cycle over.

Now, I am sure you are thinking…how do I know which one to pick and which is best? The answers to these questions really depend on what you are looking for in a filter. Do you want the cleanest water, the least amount of maintenance, or the least expensive to maintain?

If cleanliness is your forte then the DE is definitely the way to go. DE filters debris down to 3-5 microns in size, to give you an idea of how small that is, consider that a dust mite is 250 microns. If little and worry-free maintenance is your concern, the a cartridge filter is probably the best option for you as there is no need to backwash and cartridge filters are very easy to clean when they do need it. If you are pinching pennies like most people are in our current economic times the sand filter is going to be the least expensive of the three options to maintain. Sand only needs to be replaced about every 4-5 years and sand is cheap.

It is important to keep in mind that as long as your filter system is maintained properly, along with proper water chemistry, any of these systems will keep your swimming pool water clean and safe.
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