Swimming Pool Filtration

Mechanical Filtration:

Filtration of your swimming pool, could have been considered a part of the earlier cleaning process, which included vacuuming, leaf netting, emptying out of the baskets, etcetera. However, the distinction justifying the separation here, is that the mechanical filtration process, driven by water being forced through the filter, extracts particles from the water; particles that are far too numerous and far too small for any kind of manual removal. The mechanics of doing so are complex enough to warrant giving filtration it's own heading or section on the imaginary Golden Triangle.


Chemical Coagulators:

These coagulators, are products which assist in this mechanical filtration process, by causing very small dust particles, (ones that normally pass right through a filter), to "bunch up". These particles are then easily trapped by the filter and removed from the swimming pool's water. This product is used in response to cloudy water due to dust, not algae. These coagulators are available at any well stocked pool store.


Chemical filtration:

There are products in the marketplace which can cause specific minerals to precipitate (fall) out of your swimming pool's water. The residue can then be vacuumed up.



Natural Mechanical Filtration:

The "Electrically powered" mechanical filtration is not the only particle removal process occurring in your pool. Natural filtration takes place in a swimming pool, by the action of gravity pulling down on all of the dirt, dust and debris that enters the water and by the slow circulation that is driven by uneven heating of the water by sunlight. All of which, given enough time, will cause the dirt, dust and debris to end up on the walls, or floor of the pool. Which then can be removed by vacuuming or by the automatic cleaner. The same process keeps the oceans, lakes, rivers and ponds relatively clear and free of larger, heavier particles.

A friend of mine has run his pool for over two years utilizing natural filtration. He does not have a regular filter on his pool. As the bottom and walls of the pool becomes dirty, he vacuums the debris directly out of the pool. He does keep the chlorine and pH at normal levels. The pool has remained clear throughout this time. He does not swim in his pool, although he could. This is not as unusual as it seems:

In the earlier part of the last century, in the city of Los Angeles, around Hollywood, swimming pools did not have filters. What was done is to have two swimming pools, side by side, one empty although clean and one full of water and in use. When the pool that was in use became dirty, the water was transfered by a pump to the clean, empty pool. The dirty pool was cleaned up, and used again when deemed necessary. This was only possible due to the process of "natural filtration".


Unfilterable Pollutants

Water that has been naturally filtered, and purified by chemical absorption, adsorptions or by soil sediments, will present itself as either an artesian spring, or a deep aquifer. This type of water has been purified by many layers of rock, gravel, sand, and sediment, and is generally safe to drink or swim in, as long as these actions are taken soon after the water is removed from it's naturally occurring reservoir and as long as no natural or man made pollution has taken place.

Natural pollution for instance, can occur in aquifers existing in volcanic rock formations. In this instance, radioactive isotopes may be present at levels that cause real health concerns. If used for drinking, bathing or swimming, then exposure to a known carcinogen has occurred.

Arsenic is present naturally in rock formations in many areas of Arizona, but is also a residue contaminate from mining processes. Arsenic is a frequent pollutant in Arizona artesian springs, and deep aquifers. I have considered that reverse osmosis, or perhaps a water softener might be of use in removing this sort of contaminate. But, this is not an area within which I have much direct knowledge.

Arizona surface or ground water may have many types of pollutants. But, I was never very worried about drinking or swimming in water from the tap anywhere in Maricopa County, as long as the tap water I was drinking was from a combination of local well water and Verde, or Salt River water. However, once Colorado River (Central Arizona Project) water began to be introduced into the tap water, I noticed a degradation in the taste and purity of that water. The water out of the tap was much harder, with a increased level of Total Dissolved Solids.

This water, when used to fill a pool, often times could be seen to be actually green, with living algae present in the tap water! I have seen this occur in Scottsdale and Glendale tap water. Yuk. I reported this situation to the water department of each city as it occurred. The Scottsdale water department responded immediately. The Glendale water department official did not believe me. I told him to come on out and take a look for himself. All my customer's neighbors have!

This Coloradoized kind of tap water makes it much more difficult to control what is happening in your pool. You may remember from an earlier post about the negative effects of hard water and high evaporation rates. Unfortunately, there is no way to filter out these negative qualities. They can only be managed.

In the next post I will begin the discussion on individual filters types. There are three main types of swimming pool filters in use. They are the cartridge, sand and diatomaceous earth filters. The cartridge filter will be the first up.