Basic Principles
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Cat. No. 01024514
Basic Principles
Activated Carbon Filter
Filters reduce unpleasant taste and odors from the water supply. In normal operation, the water passes through the multi-
port valve into the top of the media tank. As it flow down through the mineral bed, sediment in the water is filtered out and
objectionable dissolved gases are absorbed into the mineral. The clear water that leaves the bottom of the media tank and
goes into the service lines is free from many disagreeable taste and odors.
Depth Filter
Depth filters filter both heavy sediment and suspended matter from the water supply. In normal operation, the water pass-
es through the multi-port valve and into the top of the media tank. As the water flows down through the mineral bed, sed-
iment in the water is filtered out. The clear water that leaves the bottom of the media tank and flows through the service
lines is free from most sediment and suspended matter.
Greensand Filter*
Culligan’s standard Greensand Filters operate as a continuous feed system similiar to a depth filter and not as a batch
style system. Greensand can remove manganese and both oxidized and soluble iron using a chlorine-injection feed
system ahead of the filter. Reconditioning frequency is dependent on filter loading, but a maximum chlorine demand of
10 mg/L is recommended. Desludging tanks or alternative methods of reducing the chlorine dosing may be required. This
system is not recommended for removing high levels of sulfur.
Filtering Process
To keep the filter operating properly, it is necessary to periodically remove the accumulated sediment from the mineral
bed. This done by a three-step process:
Backwash
The direction of flow through the tank is reversed, and the mineral bed is backwashed. This action expands and agitates
the bed, releasing the sediment that is then carried up and out to the drain.
Settle
The tank is allowed to be in an idle state to tallow the different types of media to stratisfy and settle. Water flow to the
drain will be present during this step.
Fast Rinse
A rapid downflow flush repacks the mineral bed and washes out traces of sediment not removed by backwash.
Backwash Frequency
Generally, backwash the HE 1.5 filter once per week. However, more frequent cleaning is recommended for water with
high turbidity. On filters with pressure gauges, the differential pressure across the filter can be monitored.
Carbon, depth and greensand filters should be cleaned when the differential pressure across the filter increases by 8–10
psi over the pressure differential across a clean filter bed.
*Greensand filters are not WQA or IAMPO certified.
