Hydrotech Water 15010670, Installation And Operation Manual, Page: 8 / 26

8
Sizing Requirements
This unit is factory set for backwash every 4 days. More frequent backwash may be re-
quired based on water conditions and amount of water used.
Water Pressure
The water system must have a pump big enough to deliver the recommended backwash
rate with a minimum pressure at the inlet of the filter of 30 psi. If the existing system can-
not do this, it must be upgraded to do so. Whenever possible, the water system should be
adjusted to deliver at least 30 psi for even more satisfactory results.
Backwash Flow Rates
The most important criteria in sizing an iron filter is the capacity of the pump. The water
must pass through the filter media at a service flow rate that allows it to oxidize and collect
the iron. The filter must also be backwashed at a flow rate sufficient to dislodge and remove
the captured iron. Failure to provide sufficient water will cause a build-up of iron in the filter
media, impairing its iron removing ability and resulting in iron bleeding out into the service
water. In order for your filter to backwash and rinse properly, your pump must be capable of
providing the backwash flow rates indicated on page 4.
Check Your Pumping Rate
Two water system conditions must be checked carefully to avoid unsatisfactory operation or
equipment damage:
1. Minimum water pressure required at the filter tank inlet is 20 psi.
2. Measuring the pumping rate of your pump:
With the pressure tank full, draw water into a container of known volume, and measure the
number of gallons drawn until the pump starts again. This is draw-down. Divide this figure
by cycle time and multiply the result by 60 to arrive at the pumping rate in gallons per mi-
nute (gpm). To aid in your calculation, insert the date in the following formula:
DRAW-DOWN ______ ÷ CYCLE TIME _______ x 60 = PUMPING RATE ________ (gals)
(secs.) (Gpm)
EXAMPLE:
CYCLE TIME is 53 seconds. DRAW-DOWN is 6 gallons; then, PUMPING
RATE equals:
6 gallons ÷ 53 seconds x 60 = 6.8 gpm
See chart on page 3 for minimum flow rates.
NOTE:
If your pumping rate is inadequate for the model, do not install your filter until
the problem has been corrected.
Backwash Frequency