Factors That Influence Your Pool Water Chemistry; Cyanuric Acid; Sodium Bicarbonate - Davey DPLGEU Mode D'emploi

10.2 FACTORS THAT INFLUENCE YOUR POOL WATER CHEMISTRY

10.2.1. Cyanuric Acid:

• Cyanuric Acid (aka Stabiliser as explained in Section 3) is used in swimming pools that are exposed
to UV, to help retain Chlorine in the water and limit rapid Chlorine breakdown. Davey recommends
following the Cyanuric Acid range shown in Section 10.1.
What is not commonly known is the effect Cyanuric Acid has on ORP (also defined in Section 3).
It should be realised that your pool water's ORP can be reduced by an increase of Cyanuric Acid
(refer Figure 10.2).
850
800
750
ORP
(mV)
700
650
600
Figure 10.2
This reduction of ORP can be confused by Lifeguard to be a low Chlorine level. In reaction to the
perceived low Chlorine level, Lifeguard will increase it's Chlorine production (unnecessarily) and
elevate the Chlorine level in the pool.

10.2.2. Sodium Bicarbonate:

• Sodium Bicarbonate (aka Buffer as explained in Section 3) is used in swimming pools to increase a
pool's Total Alkalinity, to assist in the control of pH balance. The recommended Total Alkalinity range in
most pools is 80-150ppm.
What is not commonly known is that adding Sodium Bicarbonate to a swimming pool also will also
(temporarily) cause pH fluctuations. This "pH bounce" must be acknowledged as it will affect Lifeguard's
ability to control pH during the time. It is recommended that immediately after a dose of Sodium
Bicarbonate, the pH control side of Lifeguard should be switched off (refer Section 8.1.3). The effect
should be considered proportionate to the pool volume and the quantity of Sodium Bicarbonate being
added. For example, to add 2kg of Sodium Bicarbonate to a 30,000L (30m
the automated pH control be switched off for 24 hours. Similarly, if 4kg of Sodium Bicarbonate is added to
a 30,000L (30m3) pool, it is recommended that the automated pH control be switched off for 48 hours.
CYA Oxidation Potential
0 10 20 30 40 50 60
CYA (ppm)
63
▲ CONTENTS
70 80
) pool, it is recommended that
3