Even the most simple and economical water filter system’s design should abide by the reference guideline used by water treatment professional worldwide. Failing which, the apparently clean treated water may turn out more toxic than raw water.
Insisting to do it right, we did our best to comply with the tacit rule of water treatment. Hence, the following features are very different from the rest.
(including installation)
Cheap and easily available PVC pipe are made for water to flow through the
internal wall. However, when installed in the filter tank, water also comes in
contact with the external wall and allows the sand media to rub against the
external wall of PVC pipe during backwash.
No large-scale professional sand filter would install a top strainer in their system because it restricts the trapped sediment from draining out efficiently during backwashing.
We can afford to discard it because we only load the entire media into the tank on-site, during installation. Contrary to the pre-filled media tanks in the market, we do not have to worry that the already filled-in sand would run into the multi-port valve during transportation.
The following engineering factors are widely recognised by water treatment professional worldwide, in sizing the tank coupled with specific sand media:-
Service flow (gpm/sq ft) : 3-5
Backwash flow (gpm/sq ft) : 15-20
From the above figures, the required flow for backwashing is obviously much higher (around 4 times) than that of the service flow. The reason behind such strong flow during backwashing is to ensure sufficient lifting force to efficiently dislodge the trapped sediments against gravity. However, during service run, slower flow ensures better filtered water quality.
Another plus point of loading the sand media into the filter tank on-site is maintaining transparency. Our greatest niche is the additional procedure called “Air Scouring”; a standard procedure done by all large- scale professional water filter system, including every municipal treatment plant worldwide. For your information, no one can guarantee that the graded sand has been thoroughly cleaned by chlorinated water at the quarry. The most that ordinary installers can do for you is to repeat the usual backwash after installation. This procedure is unable to lift up dirt or sediment which are trapped deep below the surface of the sand media. It is well-proven that air scouring is able to lift up the impurities onto the surface Of the sand bed, which later on, are easily drain Off by normal backwash.