It is altogether a very good and beneficial idea, every few pool seasons to rejuvenate your pool filter. Not only does this improve filtration, but is the best way to keep your pool water clean and clear without a lot of chemicals.
With my own pool, my goal is always to be able to see a dime at the bottom of my pool. 30 years ago, I might be able to read the date on the dime, but now I'll settle for seeing it clearly.
Sand Filter Rejuvenation:
Lets start with sand filters, I'm from the old school of thought that above ground sand filters should change the sand every year. On an inground filter I would change the filter sand every 3 to 5 years. To some that may be excessive, but your filtration and water clarity will definitely be as good as it can be. Some people like to just remove the top 2” of the sand bed; the crusty, oily top layers of sand, and replace with new. Good idea, but if your going to all that trouble, why not go all the way and change all the sand?
If you want to avoid changing the sand so often, use a sand filter cleaning chemical that you put in through your skimmer to clean a sand filter. It breaks down oils and minerals between the sand grains, but does nothing to improve the sand itself. Over time, the edges of sand grains become rounded, until it's like trying to filter through ping pong balls - not very effective.
There are sand substitutes available which offer better filtration and you use less of it than regular filter sand. FilterGlass and ZeoSand are two sand alternatives that filter much better than regular filter sand, and Zeosand actually has some ability to trap heavy metals and ammonia. I have used both products, and both will filter 3-4x better than filter sand, but they also can cost 3-4x as much as filter sand - but, you also use less (20% less for FilterGlass and 50% less for ZeoSand).
DE Filter Rejuvenation:
DE filters are even more critical to keep as clean as possible. I suggest at either the beginning or end of each season doing an acid bath to thoroughly clean your filter grids. Hose the grids completely clean and then bathe the grids in a large trash can, filled half full with a light muriatic acid solution mixed with water, 1 part acid added to 10 parts water. Soak for 5 minutes, then flip the grid assembly over and soak for another 5 minutes. Pull out and rinse with water, or dunk in the pool. After using the acid it is a good idea to follow up with a TSP solution to neutralize the acid, and to remove any oils and greasy residue on the grids. There are much safer products we have available such as Acid Magic, that have very low fumes and won't burn the skin but still dissolves mineral and metal deposits trapped in the DE grid filter fabric.
Just like for a sand filter there is a DE grid filter cleaner you can use also. Be sure to use a filter cleaner that is made specifically for DE grids, you do not want something too strong. Every 10 years or so you will need to replace DE grids as they just wont clean up that good anymore and they will start to develop holes in the material and areas of dark staining.
Using the correct amount of DE powder (at start up, and [less] after backwashing) will help to improve filtration and time between backwashing. Too little or too much DE powder can reduce your filter's effectiveness.
Like filter sand, there is a DE substitute called AquaPerl which uses half as much as regular DE. It's made of cellulose paper pulp, so it's environmentally friendly too!
Cartridge Filter Rejuvenation:
Last is the cartridge filter. Cleaner filtration than sand but not quite as clean as DE. it is the most popular choice for its ease of use and clear filtration. A good idea is to have 2 sets of cartridges so when you take one set out to clean you have a 2nd set to put right back in. The one thing that most people do not do is after cleaning the cartridges is to let them dry completely, that will give the cartridge a longer life and kill any bacteria or algae deep in the pleats.
Just like for the others, there are cartridge cleaner chemicals. Again, be sure not to use sand filter or DE filter cleaner, but one that is specifically for cartridges. I like to use Filter Perfect for cartridges, it removes both greasy and salty deposits. You can also use the muriatic acid and water solution (10:1) to remove just mineral deposits, good for pools with hard water, high TDS.
You can also use a small amount of AquaPerl which does increase the efficiency of the cartridge by adding another filtration layer. You'll notice over time, that either the water doesn't look so good anymore, or that you have to clean the filter twice as often as when they were new. So, it is a good idea to replace cartridges every few years, or after about 12-15 cleanings.
Keeping your pool filter at its optimum performance by rejuvenating your filter media will keep your pool water cleaner and clearer with less work on your part, allowing you to spend more time enjoying your pool, not working on it! When water is over-filtered, it needs less pump run time, less chlorine, and less attention from you!
SPP Pool Expert