How's Your Filter? The Trio - Part I
by Rob, June 19, 2008

The Trio for Clean and Clear Pool Water - Remember the Trio necessary for clean and clear pool water

Filtration, Circulation and Sanitation.

I always like to use the analogy that - if you had a filter as "big as a house" you wouldn't need worry about circulation and sanitation. Or - if you dumped in 5 gallons of bleach every few days, you wouldn't need to filter or circulate much either. Or imagine circulating your pool water so fast, like a rushing river - turning it over at a rate of 1,000 GPM (gallons per minute) that Sanitation (chlorine) and Filtration becomes unnecessary for clean and clear pool water.

In practice and in fact however - there needs to be a balance between all three elements, to ensure clean and clear pool water. So, we use a little bit of sanitation, a measure of filtration, with a healthy dose of circulation - in the correct proportions that work foryour pool.

In many cases, many pools that have problems with clean and clear pool water or the lack thereof - are suffering in only one of the three areas. Do you have problems with cloudy pool water? How about swimming pool algae? Do you backwash monthly - or weekly? How much chlorine do you need to use to keep the water clear? Today we are looking at one element of the Trio FILTRATION. So, I ask you?

How's your Filter?

Whether you have a DE, Sand or Cartridge filter on your swimming pool - some filters run better than others. Make sure your filter is not too small for your pool. Bigger is Better when it comes to pool filters. Secondly, you should know that a DE filter is a much better filter than a sand or cartridge in that it is capable of filtering the water down to a ridiculously low level of 2-3 microns. Sand or Cartridge pool filters can filter down to 20 microns - all else being equal. But as filter media ages, cartridge material breaks down with each cleaning, allowing more small particles to pass through, unfiltered. Pool sand beds can develop worn channels or paths of water flow. Sand also gets "tired" after a while and the edges get rounded. Add a pump that is maybe too large, pushing way too much water through the sand or cartridge and you can have really poor filtering. So then – a sand or cartridge filter can filter down to 20 microns, or it can be as high as 50. (Our eyes start to see particles in the 30-40 micron range).

Hint - if you have a larger filter, you can realize savings in how long of time you need to run the pump and also in how much chlorine you need to use to keep the water clear.

Hint - Change your filter sand every 5-7 years, or when it seems as though your backwashing twice as often as you used to... the sand over time loses it's sharp edges and this makes it filter less effectively. Changing pool filter sand is easy. You can usually find Pool Filter Sand in home stores, or at Stone & Gravel places (look in the phone book).Make sure that the bag reads "Pool Filter Sand". It should be cleaned and graded, 45-55 mm in size, also known as #20 Silica Sand.

Hint - Change filter cartridges every 2-3 years, more or less - depending on how much work you have demanded of them. Like filter sand, the determinant is the length of time required between cleanings. When you have to backwash your sand filter or clean your cartridges every week, it's time for new pool filter media.

Hint - Change DE filter grids when they develop holes in them. You should remove the DE grid assembly every 4-6 mos - from the tank to spray it completely clean. Using Filter Cleaner is a good idea every 12-24 mos to remove oils and mineral deposits from the porous fabric. As you hose DE filter grids clean, inspect them for holes or tears in the fabric.

Hint - Use the pressure gauge as your guide. Backwash or clean the filter when the pressure gauge rises 8-10 lbs above the clean, "after backwash" pressure.

Bonus Hint: Pressure gauges are cheap instruments - Don't bet your life on them. Sometimes they lie. Sometimes they stick - give them a flick of your fingernail when you check them - to make sure they are responsive.

Give your filter a check - maybe it's time this year to change the sand or cartridge or de filter grids. Or maybe things are going well. A good sized filter should be able to keep your water clean and clear with only 12 hours or so per day of operation. But that depends on Circulation, doesn't it? That's what we'll look at next time in our look at the Trio ~ Filtration, Circulation and Sanitation. Until then, enjoy your pool!