Swimming Pool Blog
Rob Cox, March 9, 2012
"When should I change my pool filter media?"
If you've not heard the term Filter Media before, I apologize; it may be more of an Industry term for the material used inside the filter tank to trap the dirt.
For swimming pool filters, we have 3 types of Filter Media: Sand, Cartridges or Grids. Over time, all of these filter media types will need to be replaced.
Here's how to know when that time will be.
Lifespan of Filter Media Types:
Under Normal conditions, for well-maintained pools, Undersized filter systems or poor water balance can strain your filter media. In fact, the large range for cartridge filter replacement depends on how well sized the pool filter is. Larger pool filters, with more filter surface area, require less cleaning and changing of the media.
- Pool Filter Sand: 7-10 years
- Pool DE grids: 7-10 years
- Pool cartridge: 2-5 years
Signs that your Filter Media may need to be replaced:
- Filter requires more frequent backwashing or filter cleanings
- Increased filter runs required for clear pool water
- Reduced water clarity and sparkle
- Dirt or DE powder coming back into the pool
- Filter clogs easily, often during vacuuming
- Skimmer suction is not as strong as before
- Difficulty maintaining water balance or an algae free pool
How to inspect your Filter Media and evaluate it:
- For sand filters, it's hard to inspect the filter sand, because you will need to remove the top dome, with the special wrench, or you may need to cut pipes to remove a top mounted multiport valve. But if you were to inspect your sand filter sand bed, here's how I do it.
After draining the filter tank and gaining access from the top, reach into the sand with your hands (Side mount tanks: move the baffle to one side, out of your way). Run your hands through the top few inches and see how many "mudballs" you come up with (ewww!). Then, run deeper, looking for calcification of the sand, or hardened areas. Although rare, try to spot any channeling of the sand. Inspect the sand under a magnifying glass, if you want to really geek out, sharper edges are good, rounded edges are what happens to worn out filter sand.
If you are thinking about changing your own pool filter sand, it's not so hard to do. We did a video last spring on how to change pool filter sand.
- Cartridge filter elements, get inspected everytime you clean it, right? It's impossible to see the clogging of the pores inside of a cartridge filter; they clog over time, with small minerals and oils. Most filter cartridges are spun Reemay, a type of polyester, and the fibers do a great job of trapping micro-particles, while allowing water to pass through. Over time however, and the fibers loosen, trapping dirt deeper inside, where you can't get to it with your garden hose, or allowing dirt to bypass the cartridge and return to the pool.
Each time you clean a cartridge pool filter, it loses a bit of efficacy, or water filtering ability. The cleanings will become more frequent, and then you may have trouble keeping the water clear, and then comes an algae attack that you can't seem to kill completely. All signs that you need to change your filter cartridges. Even though they aren't cracked, or split, or completely falling apart, they can be doing only half the work of when they were new.
Generally speaking, inspecting a cartridge filter won't tell you if you need to replace it, but paying attention to these other things will. If you are having no water problems at all, and you only need to clean the cartridge(s) every month or two, then you're probably OK for now.
- D.E. filter grids don't really do the filtering; it's the powder, you know. But the powder gets replaced each time we backwash, and the grids will last 5, 10, maybe 15 years. Eventually though, the fabric will wear, the seams will tear, and you will need to replace the filter grids.
To inspect DE filter grids, first shut down the system and open the air bleeder. Remove the tank clamp band and pull off the filter lid. Pull the grid assembly up and out of the tank, to a level area where you can clean it. Hose the grid assembly very thoroughly (this should be done 1-2x per year for DE filters). Inspect the grids and sewn seams as you clean it. Discoloration is not uncommon, and may not indicate that the grids are clogged.
DE Grids can also become clogged with minerals and oils, and if you are having de filter pressure problems, and you are using enough DE powder, you may benefit from giving your filter grids a cleansing bath in our pool filter cleaner chemical. If cleansing the grids very thoroughly does not solve the problem, grid replacement may be in order.
The other time to replace your filter grids is when they start to tear and rip. If the whole set is fairly new, you can just replace an individual grid. Or if you're handy with an awl, de grids can be patched or sewn. If the grids are older than say, 7 years - and some are starting to tear, it may be best to replace them all, with a universal grid set (7 lg, 1 sm). We did a recent blog post on how to replace a DE filter grid set, and get it all assembled again!
Well, that's all I got for now - pay attention to your filter, it sort of lets you know when you need to replace the filter media!
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