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Pool Filter

The swimming pool filter is the reason your pool water is clean and clear. The name pool filter says it all. The swimming pool pump will pump pool water through the swimming pool filter where unfiltered water passes through and clean, clear water passes out trapping almost all particulates, debris, dirt, and coagulated products in the pool filter. Pool sanitizer (chlorine usually) keeps the pool water sanitized and free of micro-organisms that can grow in unsanitized water. Perfect pool water chemistry combined with a sound swimming pool filter results in clear, blue, and sparkling pool water.

There are three popular types of swimming pool filters in California. They are sand, cartridge, and diatamaceous earth. We will refer to diatamaceous earth as d.e. from this point forward. The most popular swimming pool filter is the d.e. filter, but cartridge filters are becoming more popular, because they are considered to be the more environmentally friendly swimming pool filter choice. The sand filter is the easiest and cheapest to maintain, but offers less micro filtration compared to the other two. The d.e. filter offers the finest, most micro filtering pool water among them all and is the most popular, so we are going to focus on it with this page.


Inside the d.e. pool filter, you have a grid assembly composed of 8 grids, a grid retainer,a manifold that holds them together in formation, and a metal center rod tightened with nuts to lock them in for one complete grid assembly. Pool water will pump through the exterior of this grid assembly and clean, filtered water will flow through the cloth and d.e. into the inside of each grid and out the filter through the inside of the manifold.

One of the benefits of the d.e. swimming pool filter is back-washing. Back-washing is where water flow is reversed inside the pool filter and pool water return flows out to the house sewer or other plumbing line then back to the swimming pool. Back-washing cleans the inside of the pool filter by washing out the d.e. and dirt that coats the filter grids.

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Diatamaceous earth coats the filter grids, so dirt and debris does not stick or cake on to the grids. Dirt, debris, coagulated particulates, and other products then get trapped by the d.e. coating the grids. Back-washing washes the d.e, dirt, and debris out of the filter and lowers the pressure inside the filter for efficient filtering. 

Back-washing cleans the filter without dismantling and is recommended whenever the pressure starts rising from the pressure marker you should make whenever you dismantle and clean your swimming pool filter. We will back-wash pool filters 3 or 4 times before dismantling and cleaning. Most swimming pools in California need a filter dismantle and clean once or twice a year thanks to this backwashing capability.

Back-washing also helps to drain pool water in the event of overflow from rain or overfilling. We are experiencing a drought in California at the time of this writing, so please take care when filling your pools with water. Back-washing is another advantage compared to cartridge filters since they don’t have backwash valves.

We always add fresh, new d.e. after a backwashing or annual filter dismantling and clean. We do this by pouring the d.e. down the pool skimmer with pump suction on (just like the picture up and to the right), so the d.e. is sucked into the filter grid assembly inside the swimming pool filter. We try to always inspect return water out of return lines after pouring d.e. down the skimmer to confirm that the swimming pool filter is capturing and holding the fresh d.e.


Only swimming pool repair experts should attempt pool repairs such as a swimming pool filter dismantle and clean!!


Once or twice a year in California, our swimming pool cleaning service will perform filter dismantle and cleans. We will inspect all the grids and manifold for cracking or holes. Any holes or cracks will cause dirt and debris to return back to the swimming pool which ruins our filter process. We will replace all compromised parts we find in this inspection including the tank o ring which needs replacement every year or two.

A Symptom of swimming pool filter issues is noticable d.e., dirt, or debris piling up on the bottom of the pool around pool or spa return lines. This is because holes in the grid assembly will allow debris, dirt, and d.e. to pass through and out to pool return lines where they will fall down to the bottom of the swimming pool. A good test for this is to backwash your swimming pool filter and see if you notice cloudy water or tiny particles returning out your pool or spa return lines right directly after adding d.e. to your swimming pool filter.

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Valuable information to enhance your pool and spa experience!

The 3 most popular pool filters in Tustin are the diatamaceous earth filter, cartridge filter, and sand filter. Diatamaceous earth or d.e. is the most popular pool filter in Orange County, Ca. Cartridge filters are gaining in popularity though and Sand filters are the least popular.

A Cartridge Pool Filter is More Green

cartridge pool filterCartridge filters are considered the green filter (environmentally conscience). This is, because they do not have backwash valves which means less waste of pool water. You will find the cartridge(s) with ridges look much like a car air filter. They filter better than the other filter types at low pump speeds and have more inside filter surface area.

Cartridge filters have no backwash process, so they need dismantling and cleaning more often. This means more maintenance and expense. They also do not filter pool water as clear as d.e. filters. Many people would not notice the difference though. Another issue is holes and tearing are less obvious due to the ridges. It is very hard to see holes or cuts in the cartridge cloth like d.e. filter grids.

The lack of back-washing and greater efficiency to filter at lower pump speeds is why many call them the green filter. There are times where backwashing is convenient to drain pool water such as rain or flooding though.

The D.e. Pool Filter is Most Popular

The most popular and finest micron filtering pool filter is diatamaceous earth. A manifold and grid spreader secure the d.e. filter grids. D.e. is poured down the pool or spa skimmer to coat all the pool filter grids. The d.e. keeps  keeps debris and micro-particles from sticking or caking onto the cloth of the filter grid. Filtered, clean pool water will come out of this d.e. pool filter and return to the swimming pool.

D.e. filters should be backwashed by a swimming pool service professional every 2 to 4 months.  Back-washing is a process where you reverse the flow of water through the filter, so pumped water pushes through the inside of the manifold and filter grids out the waste line. This forces d.e. and debris off of the cloth of the filter grid and out to the sewer or wherever the back-wash line is directed. Fresh d.e. will re-coat the grids for proper filtration.

You will know that your pool filter needs to be back-washed when the pressure on the filter gauge rises a couple notches above your recorded clean filter pressure. It is good to backwash your filter every 2 to 4 months if your filter pressure rises or not though. You can get 2 or more good back-washes in before tearing apart and cleaning the filter grids individually with a hose spray.

Depending on your area, your d.e. pool filter will need the tear down filter clean once or twice a year. One more advantage of d.e. filters is you can backwash your swimming pool if the water level gets high from rain or just to let some hard water out for replacement.

D.e. filters do have more internal parts that need replacing. There are usually 8 grids, a manifold, a grid spreader, and a center metal rod. The grids and manifold should last 3 years or more, but you can expect to pay around $300 or so to replace all the grids and the manifold in today’s dollars. Your filter grids will last longer if you keep your pool water maintained well and regularly backwash to avoid abuse.

Sand Filters are not Popular

Sand filters are the easiest and cheapest filters to maintain. The filtering media is the sand, so internal parts last a long time. They need back-washing every 2 or more months to wash out trapped debris in the sand. You will know to back-wash when pressure rises on the filter pressure gauge.

Every 5 to 8 years the sand needs disposal and replacement. That is the only maintenance besides back-washing, so ease of regular maintenance is an advantage.  These are more popular in areas with lots of dirt and sand that end up in swimming pools. Sand filters do not filter down pool water as fine as d.e. or cartridge filters, so the weakness is pool water clarity is less.

In conclusion, the d.e. filter will provide the clearest and most pure pool water. The expense for parts on the cartridge and the d.e. filter are pretty close, because the cartridge can be quite expensive and you have to replace the whole cartridge for any tear or hole while you may only have to replace one or two grids that have issues with the d.e. filter. You also have to take apart and clean the cartridge filter more often due to not being able to backwash which would raise maintenance expense. In return, the cartridge filter will save pool water and work better with slow pump speeds, so they are more green

This explains why d.e. filters are more popular in Orange County, Ca. and why cartridge filters are growing in popularity. For those who can afford a little more maintenance and don’t mind a little less water clarity, going green may be worth it with the cartridge filter. Still, most people are choosing the finer filtering d.e. filter with the ability to backwash today. Having a good pool filter is just one more part of your Pool Heaven.

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