Filtering a swimming pool effectively and efficiently is essential to removing fine particles of dirt, debris, algae and organisms from pool water. And how effective the filter system is depends largely on the type of pool filter media chosen. Pool + Spa talk to Bryan Goh, Group Marketing Director for Waterco about the latest in pool filter technology.
There are myriad types of filtration media, including sand, Zeolite, glass and anthracite. Sand is a popular form of filtration, as the filter media is easily cleansed via the operation of its multiport valve. It does require a backwash line to backwash the waste of a filter. If it's not possible to install a backwash line, then cartridge filtration would be the next choice. It also requires less water to maintain the filter but requires the physical removal and cleaning of the filter cartridge.
DE filtration is known to be the finest filter, but requires replacement of DE powder on its filter grids. DE powder is also troublesome to handle. There is also a new category of filtration introduced by Waterco, which is centrifugal filtration. Minimal maintenance is required and it does not require a backwash line. However, it cannot filter floating debris, only debris that sinks.
Granular filters were always the most popular pool filters, largely due to how convenient they are to clean. All you need to do is regularly backwash the pool water through the filter media to remove all the trapped dirt and you're done.
In recent times, however, pool filtration systems that are economical to run and have the environment in mind are becoming increasingly popular.
Environmentally Friendly Filters
Over the past few years there has been a significant move to green solutions, with pool owners looking for chemicals and equipment that are more eco-friendly. And there's now significant pressure on the industry to develop energy efficient products, with a number of manufacturers including Waterco working to meet this demand (see Product Watch for more information on environmentally friendly filters).
Perlite is a filter media that can be used instead of DE. Cartridge filters are increasing in size to reduce their frequency of maintenance. Other developments are centrifugal filtration, as mentioned above, and centrifugal filtration combined with cartridge filtration in the one housing. With regards to commercial swimming pools, nozzle plate filters and DE filters are the latest in filter technology.
I see further development of centrifugal filtration technology, automation of media filters and the improvements on energy and water efficiency.
For commercial applications, I would recommend a nozzle plate filter with glass media and equipped with air scouring to reduce the amount of backwash water required. Waterco hopes to introduce its commercial sized MultiCyclone in approximately six months' time.
In a domestic pool I would recommend either a glass filled Micron ECO filter equipped with fish tail laterals to minimize backwash water, or a MultiCyclone with an Opal XL cartridge filter to minimise filter cartridge maintenance.
If the wrong filter is chosen the ramification is a poor filtration ability, leading to cloudy water, or a filter requiring frequent filter maintenance as a result of being undersized, or the filter media not being cleaned/serviced adequately. Also if the flow rate is excessive beyond the filter's maximum flow velocity, the filter will not perform at its optimal level.
I would advise to lower the flow rate through the filter as low as possible, but still maintain enough flow rate to meet the pool's minimum turn over requirements. Slower the flow of water through the filter media, the better the result. I think the industry should aim to lowering filter flow rates, which can be achieved by the introduction of variable and multispeed pumps. But if filters are designed to be more hydraulically efficient with more hydraulically balanced filter laterals, lower backwash rates can be achieved, which means smaller pumps, lower flow rates which equals to better energy efficiency, water efficiency and better water clarity.
We have witnessed a huge interested in glass media. Waterco has introduced its glass beads with great success. Being manufactured and not crushed enables a low uniformity coefficient to be achieved, which means a narrow sized range. This results in a very tight filter bed, with extremely narrow pathways, resulting in the finest filtration achievable via a media filter.
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