There are three choices when it comes to swimming pool filtration. The three options available are cartridge, sand and Diatomaceous Earth (DE). If your too lazy to read the rest of the article and want a middle ground reliable filter you can stop reading and decide on sand. For those of you who want more information, I’ll break down the pros and cons of each.
Starting with the cartridge filter, it is the filter that only traps the largest particles of dirt. This filter type looks and operates similar to the air filter you use in your home air-conditioning system but rather than trap allergens it traps particulate through it. The clarity of the water is dependent on the cartridge itself, but because a rather large amount of water needs to pass over the cartridge quite quickly, they allow the most amount of particulate to pass through unfiltered. The unpleasant part of using this type of filter is the manual cleaning. Several websites and even the cartridge manufacturers recommend soaking the cartridge in a dilute of tri-sodium phosphate to clean. So, to minimize down time that would mean you would need two cartridges, and a large plastic garbage pail. Swap out the clean filter cartridge for the dirty one, and place the dirty one in the plastic garbage pail to soak. Then after several hours of soaking, remove the cartridge and hose off. An unpleasant job in cool weather as you will surely get wet. Then there is the added cost of regularly replacing the cartridges which can cost $60-$90 each.
Pressurized sand filters are the middle ground. Once you learn how to maintain and properly backwash; you may find it easier than the process for rinsing your cartridge filter. The size of the particulates that a sand filter will trap are far smaller than the size of the particulate you will trap with a cartage filter. The process behind cleaning the filter is more difficult to explain than the cartridge without diagrams, video and your model. But basically, it is simply to turn off your pump (this step is super critical, as failing to do this, and attempting to move the multiport valve while it is under pressure, can cause the rubber gasket to impinge) and turn the multiport to backwash. Wait a few minutes until the sight glass runs clear, then turn the pump off, reposition the valve to rinse, turn the pump back on and run for a minute. Turn the pump off, reposition the valve to filter, turn the pump back on, and you are done.
The process involves changing the direction of the waterflow to stir up the sand bed and get rid of the particles trapped between the grains of sand. This process expells them through a wastewater hose. At this point some particulate may still pass through the sand filter until it is compacted again so you change the waterflow back to normal while allowing it to dump the water through the backwash hose. Then you redirect the flow to your pool. Now you’re done. It may seem complicated at first but, the process becomes quite simple over time. When you need to backwash will be determined by the pressure gauge on your filter. This is visible on the dial attached to your filter, once it reaches red it’s time to backwash. When properly maintained the sand can last up to 10 years without replacing.
Diatomaceous Earths filters (DE filter for short) are like sand, but capture even smaller particles. The pressurized filter chamber looks like a sand filter’s. It pushes water over a compressed bed, like sand filters, but uses a smaller medium than sand filters do. DE stands for diatomaceous earth, which are the skeletons of dead single celled silica based organisms. The problem with smaller particle capture is they need to be backwashed more often and the DE needs to be added back into the system on a regular basis as it slips out of your filter more readily than sand. I have a DE filter and while it keeps my water crystal clear, I maintenance it more than I would like.
The procedure for cleaning the DE filter is identical to that of cleaning a sand filter, except that now, you have to go to your garage (or storage shed) and get the DE powder and add it to the skimmer after each backwash cycle.
I will note however, that the difference in water clarity across all three of these methods is rather marginal. If you maintain your water chemistry and filters, the difference in clarity is not easily discernable by the human eye. I would recommend picking one that meets the best balance between how clear you want your pool to look and the amount of time you want to spend keeping it that way.