CARTRIDGE SWIMMING POOL FILTERS

Cartridge filters: Filter of choice for most spas, and many smaller above ground pools, the Cartridge filter is enjoying a resurgence in popularity. The cartridge filter element, an aquatic version of the pleated air cleaner in your car, traps dirt and particles of 25-100 microns in size. The cartridge is removed from the tank and hosed thoroughly, top to bottom with a high pressure hose to remove dirt when the pressure gauge rises 8-10 lbs. above its clean reading. I know some cartridge filter owners that take their pool cartridges to the local self serve car wash place for cleaning. Each time the cartridge pool filter is cleaned, some of its filtering ability is reduced. The cartridge should be replaced every 2-5 yrs, depending on the work it was asked to do. If the filter was a bit undersized, and had some algae every year and lots of tree debris, etc. then it may last only 1-2 years. Nicely sized cartridge filters can operate for 6 months between cleanings. A general rule of thumb is to buy at least 100 sq ft of Cartridge Filter surface area for each 10,000 gals of pool water in your pool. Some say that a cartridge pool filter is not the best type of filter, but when properly oversized, a cartridge filter can go an entire season without the need to clean the filter cartridges.

"How do I Backwash my Cartridge Filter? A trick question. There is no backwash valve on a cartridge filter because today's pool filter cartridges aren't built for reverse flow. Instead, the pump is shut off, air bleeder opened, lid removed, cartridge removed, hosed thoroughly Top to Bottom, and replaced. It's a bit of a pain to do, but hopefully the filter is sized so that it's a 1-2 x per year job.  Another advantage is that cartridge cleaning doesn't waste as much water as backwashing.

Soaking the cartridge in a TSP or similar solution prior to hosing will improve your cleaning. Do not use TSP if you utilize Baquacil or Soft Swim for sanitation. There are also commercially available cartridge cleaning solutions that will help dissolve certain oils, salts and other minerals.

Use of a clarifier or Chitin product like Sea-Klear is a great help to a cartridge filter. Some people also increase the filter efficacy by adding a small amount of synthetic filter aid powder (1-2 cups) through the pool skimmer. DE powder is not recommended by most manufacturers, as it can clog the pores of the cartridge. (but secretly, we sometimes use a little bit, on cartridge filters that are undersized, to help improve filtering ability of the pool cartridge.

Disposal / replacement of the cartridge, its difficulty in maintenance (no backwashing) and its relatively low efficiency are the reasons I don't recommend these filters for use in most larger swimming pools. But for pools under 30,000 gals. there are some nice filters like the Hayward C-4000 that can really be a great filter.

Filter Cartridge Replacement: Right off the shelf for $40-100, depending on its size. No professional labor needed.