Check to see that the valve on the bottom of backwash water tank is fully open (turned fully to the left
until it stops).
Remove product water hose (14, fig. 2-30) from product water tank and allow hose from ROWPU to
drain on the ground. Leave brine water hose in backwash water tank.
(10) Start element cleaning. Push ELEMENT CLEANING switch (fig. 2-47) up to START position. Release
switch. Switch automatically goes to RUN position. Element cleaning starts.
If element cleaning does not start, it may be necessary to loosen
draincock on backwash pump to purge air. Close draincock when pump
(11) Within a few seconds, BRINE FLOW indicator (16, fig. 2-4) should show a flow of 16 gpm or more.
If pH of water circulating through R.O. elements drops below 3.5, element
membranes may be damaged.
(12) After 5 minutes, check pH (para. 2-32) of water discharging back into brine tank; it should be near, but
not below, 3.5. If it isnt, add another pound of citric acid and stir until all granules are dissolved.
If in the past, when using the same source water, brine has been very
alkaline, then more citric acid may be added; however, never let pH of
the water circulation through R.O. elements drop below 3.5.
(13) Continue checking pH and adding 1 lb of citric acid at 5 minute intervals until pH of water is near, but not
(14) Allow citric acid solution to circulate for 45 minutes. Periodically check the temperature of the water
discharging back into brine tank; use thermometer in Storage Box No. 2.
Temperature of solution will rise during element cleaning. At no time
should it exceed 120 degrees. If temperature rises above 120 degrees,
stop recirculating citric acid solution and resume normal operation.
(15) Stop recirculation by pushing the ELEMENT CLEANING switch down to OFF.
(16) Remove VENT VESSELS hose from outlet of the backwash pump and connect BACKWASH WATER
hose to backwash pump outlet.