Membership Directory & Resource Guide - 2018 - 37

TECHNICAL BULLETIN 2018 * pg 2 of 3

TECHNICAL BULLETINS

Reprinted with permission of Pebble Technology International

TECHNICAL BULLETINS

TECHNICAL BULLETIN - PREVENTING INTERIOR
The Effects of High Cyanuric Acid Levels
FINISH
&isTESTING
FOR
CYANURIC
are issues
caused by high cyanuric
The ideal levelDETERIORATION
of cyanuric acid in a swimming pool
30 - 50 ppm . There
acid levels such as chlorine efficiency and most importantly, the tested alkalinity, which can result in an
ACID
aggressive water balance.
3

Defining
Cyanuric
Acid in 2001, John A Wojtowicz summarizes his article on pool water balance and the effects
In an article
published
Cyanuric
acid
(CYA)
is NOT a chlorine - it has no sanitation properties. Cyanuric acid protects any type of
of cyanurate:
chlorine from UV (sunlight) destruction. Cyanuric acid is referred to as "stabilizer" or "conditioner" so there
are three names for the same product. When cyanuric acid is present in ideal ranges, the chlorine will remain
"Swimming pool water chemistry must be balanced in order to prevent corrosion, etching, and scaling
effective 3 to 10 times longer.1

and maintain water clarity. This is accomplished by means of the calcium carbonate saturation index
(SI) which
allows calculation of a measure of the degree of calcium carbonate saturation of pool water
Defining
Chlorines
based
on
thedifferent
temperature,
carbonate
alkalinity,
calcium
hardness
(Langelier
Larson
There are several
type ofpH,
chlorine
products
used to and
sanitize
swimming
pools.
The most1936,
commonly
Vanthe
Waters
1964).
It is desirable
used1943,
includes
following
by chemical
name:to maintain the SI in an ideal operating range so that the water
is neither corrosive / aggressive nor prone to precipitate calcium carbonate for a maximum percent of
the time.
However, the
SI varies
with
time primarily because pH and alkalinity change due to addition
* Sodium
hypochlorite
(liquid
chlorine
/ non-stabilized)
of sanitizers
and loss(granular
or carbonchlorine
dioxide,/ non-stabilized)
necessitating periodic adjustments. Since acid addition for pH
* Calcium
hypochlorite
reduction
consumes
alkalinity,
this
needs
to be/ taken
into account when adjustments are made. Also,
* Sodium dichloroisocyanurate (granular chlorine
stabilized)
if the water contains other alkaline substances (e.g. cyanurate ion), the total alkalinity must be
* Trichloroisocyanurate (3" tablet / stabilized)
corrected to obtain the actual carbonate alkalinity (Snoeyink 1980, Stumm 1981) so that the correct SI
4
is
otherwise
corrosion and
etching problems
Di-chlor can
andarise."
Tri-chlor have cyanuric acid
Please obtained,
notice the
last serious
two highlighted
chlorines.

(stabilizer/conditioner) added to the chlorine product. There is NO cyanuric acid in liquid chlorine or cal hypo.
Water balance is key to preventing issues with the pool equipment and interior surfaces. The presence of
cyanuric
acid distorts
theismeasurement
of carbonate
alkalinity.
If level
the necessary
as described
When
a stabilized
chlorine
used in a swimming
pool, the cyanuric
acid
increases. adjustment,
One 7 ounce tri-chlor
below,
is
not
made
to
the
total
alkalinity,
the
pool
water
will
then
become
aggressive
and
start
to
dissolve
3" tablet is approximately 55% cyanuric acid so the cyanuric acid increase per pound in a 10,000 gallon
pool the
2 When this dissolution of the surface starts to occur, there will be a significant loss of pigment.
interior
finish.
will be 7 ppm. The percentage of stabilizer in granular di-chlor is between 50 - 58 %. The increase of cyanuric
2
Due per
to the
hand
application
of the 6plaster,
there
can
be varying
differences
pigment
If 3"
tablets
are used,
it would in
bethe
bestamount
to use aofnonacid
pound
in crafted
10,000 gallons
is between
- 7 ppm.
loss from chlorine
one areaproduct
to the other.
stabilized
such as cal hypo or liquid chlorine to shock as there is no cyanuric acid in those
products. When a freshly filled pool is being adjusted for swimming, cyanuric acid manufacturers suggest
raising
the CYA
30 - 50 ppm.
In a southern
on awater
freshlyneeds
filled pool
that
will beweekly
using 3"with
tablets,
the to
To prevent
thistoaggressive
water
condition,climate
the pool
to be
tested
attention
5
cyanuric
acidthe
levelfollowing
should beideal
adjusted
maintaining
levelsto: 25 - 30 ppm.

Free Chlorine: 2 - 4 ppm

Total Chlorine: 2 - 4 ppm

Combined Chlorine: 0 ppm

Technical Bulletins

In-Line
7.4 -Feeders
7.6
pH: Stack Chlorine
The
convenience
of
dropping
tablets
in ausing
tube stabilized
for sanitation
is popular
must
understood is that
(when
chlorines
suchbut
as what
di-chlor
& be
tri-chlor)
Total alkalinity: 100 - 120 ppm
this is a method of allowing a continuous feed of chlorine to a pool when the pump is running. The warmer
the
water, the
faster
the tablets
will condition,
dissolve andthe
potentially
raiseneeds
cyanuric
rapidly.
To prevent
this
aggressive
water
pool water
to levels
be tested
monthly with attention to

maintaining the following ideal levels:
Sanitation
is to be done primarily
by ppm
testing and liquid or granular chlorine is the preferred method to shock
200 - 400
Calcium hardness:
the
water.acid:
The tablets will30
not- "shock"
50 ppm the pool to regain the proper sanitary properties of the water. Using
Cyanuric
a non-stabilized liquid or granular chlorine for shocking will prevent high cyanuric acid levels from increasing
to
a leveltake
of deterioration.
Finally,
the necessary measures to ensure that the cyanuric acid levels are maintained below 70 ppm.

Once the cyanuric acid level is close to 100 ppm, the best way to lower the cyanuric acid level is by draining a
portion of the water from the pool.

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