Monday, March 5, 2012
Alternative Media for Sand Filters
Alternative Filter Media for Sand Filters
Zeolite and Glass media were introduced to the swimming pool industry years ago. At that time little was known about these types of media use in pools although they had been used in other industries for water filtration. We now know much more and can make an educated decision if either of these are a choice we want to consider in our pools filtration system.
The removal of particles during filtration and the efficiency of the media are very important. With all of us attempting to be water conservative and energy efficient it is time to again look at these alternatives.
A media that has steadily gained customers is Zeolite. Zeolites can be natural or synthesized. Zeolite is a honey combed shaped structure with a surface area 100 times greater than sand. With the increase in surface area the filter is capable of collecting more dirt in a shorter period of filtration time which enables a decrease in how long you need to run your filter.
Zeolite will filter out particles down to 2 – 5 microns which is comparable to diatomaceous earth filters. This increase of efficiency also increases removal of wastes, algae and gives superior water clarity without the expense of purchasing a new DE type filter. Due to its low micron removable there is no need to use a clarifier while using Zeolite.
Zeolite has the ability to absorb ammonium compounds that are created by swimmer waste. Traditional sand filters do not have this ability. By removing the ammonia compounds there is less frequency with having to “shock” the pool, eliminates red burning eyes by reducing the chloramines in the water. This saves on the amount of chemicals you must add to the pool and saves money.
Less dense in bulk weight than silica sand, Zeolite is used at the rate of half that of sand. For every 50lbs. of sand you would use 25lbs. – 30lbs. of Zeolite. It has the same life expectancy as sand which is 7 – 15 years. You can “refresh” the Zeolite by soaking the media while in the filter in a 10% salt solution overnight. This process is recommended every 2 years. This still needs to be done with a “salt” type pool as the normal pool concentration is not high enough to properly refresh the Zeolite.
There is an increase of 2 times the duration between backwashing over sand media filters. Also the time to backwash the filter is cut by half. This saves water and also the chemicals that have been used to treat the water. When it is time to change the Zeolite media you can safely recycle it into the soil as it is an excellent soil additive or dispose of as a non hazardous waste unlike DE. There is no hazardous dust to be inhaled with Zeolite as there is with diatomaceous earth.
On the initial addition of Zeolite there is a need to backwash 3 times with a short period of time between the backwashes to allow the Zeolite to settle. This does waste some water but the benefits later outweigh this drawback.
Another type of sand media replacement is crushed glass. Although available in the states for some time it is more prevalent in Europe. A study done for CWC which is a non-profit organization that provides recycling marketing services to business and government has documented that using glass media improves water clarity by 25% over sand media, increased the backwash efficiency by 23% and 20% less media was needed over sand media.
With the increase of water clarity the filter run times can be decreased to achieve the same clarity of water. The amount of time necessary to backwash the filter was decreased saving chemical treated and heated water. Both of these save energy costs as well.
The glass particles used have the shape required to be able to remove particulates but are smoother than sand so that it is less likely to support algae growth. The surface of the glass is negatively charged and attracts iron and manganese to it. There is no silica hazard as with sand as well. It works well with “salt water pools”. It lasts 3 times longer than sand media with a 5 year minimum life.
Glass media is not as readily available as Zeolite or silica sand at this time. In discussion with distributors of this product there has been some objection by consumers to use this as the thought of glass entering the pool through a broken filter lateral would not be desirable. Hopefully we can gather more information on this product and actual use in the future.
Through the use of alternative filter media we can increase the clarity of our swimming pool water making them more inviting than ever without the use of more chemicals. We can also make them “green” by saving energy as well. You can make your neighbors “green” with envy on your beautiful pool with little effort or money.
“Evaluation of Recycled Crushed Glass Sand Media For High- Rate Sand Filtration”
CWC October 1998
Zeo : Natural Zeolite Products web page ( www.zeoinc.com)