Sere

Dre F. C. Allen page 2 October 14, 1942

(3) Feed alum into the recirculated water after each beckwashing of
the filter. This is done so that the alum will react with the naturel
alkalinity of the water to form a floc of aiuminum hydroxide over the
top of the filter. The floc aids in taking the colloidal material

and finely divided particles from the water. A pH between 7.2 and 7.6
should be maintained in order that the floc can form. One-haif pound
of aium should be added to the solution pot when the filter is back-
washed. Both the valve on the influent line and the valve on the
effluent line should be opened after the alum hes been placed in the
pot e

(4) Operete the recirculation pump end chlorinator contimously. The
rate of feed on the chlorinator will probably have to be adjusted, as
little more chlorine will be required and the feeding period will be
lengthened. The water in the pool should be filtered at least three
times each day. The present capacity of the pump and the filter will
not allow this, so it may be necessary to get lfarger units or drain the
pool more frequently.

(5) Every person entering the pool should take a shower with soap in
order to carry as smail amount of organic matter into the pool as
possible.

The addition of liquid chlorine and a small amount of alum to the water
will cause the pH to drop. This may be prevented by the addition of
lime or soda ash. It is my suggestion that you obtain severel hundred
pounds of soda ash to control the pH. This could be mixed in solution
and fed at the solution pot each day.

After the pool has been filled for two or three days with the city water,
there will be a decided tendency for the pH to drop rapidly. This can

be prevented only by careful pH control and the feeding of soda ash.

If you will let me kmow when this stage is reached, I will try to help you
get the feed adjusted. When the water has been brought beck to the pioper
aikelinity, a feed of 1-1/2 pounds of soda ash per pound of chlorine is
usually sufficient to hold the pH up.

Residual chlorine tests should be made at least three times during the
day and a record kept of the results. The residual shovld build up
during the night and will drop again during the day. The chlorine re-
Ssiduei should not be less than 0.3 pepem. or exceed 0.6 DeDeMe

Very truly yours,
DIVISION OF SANITATION :
Dwight lp, Metzier

DFii : dmb Assistant Engineer
ccs; E. Le Treece