Here is what appears in Volume 1 Number 2 of the Journal of the Swimming
Pool and Spa Industry:
General:
An Introduction to the Journal
Articles:
John Wojtowicz
Chemcon
Swimming Pool Water Balance – Part 2: Factors Affecting the Calcium
Carbonate Saturation Index
Swimming pool water chemistry must be balanced in order to prevent
corrosion, etching, and scaling 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 based
on the temperature, pH, carbonate alkalinity, and calcium hardness (Langelier
1936, Larson 1942, Van Waters 1964). It is desirable 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 of sanitizers and loss of carbon dioxide, necessitating periodic
adjustments. Since acid addition for pH reduction consumes alkalinity, this
needs to be taken into account when adjustments are made. Also, if the water
contains other alkaline substances (e.g., cyanurate ion), the total alkalinity
must be corrected to obtain the actual carbonate alkalinity (Snoeyink 1980,
Stumm 1981) so that the correct SI is obtained, otherwise serious corrosion and
etching problems can arise. A previous article (Wojtowicz 1995) showed how to
correct total alkalinity for the effect of cyanuric acid.
Kim Skinner and J. Que Hales
Pool Chlor
The Addition of Muriatic Acid – Results and Implications of Using Varied
Methods of Muriatic Acid Application in Swimming Pool Water
The lowering of Total Alkalinity (TA) and/or pH in swimming pools utilizing
muriatic acid has been an accepted procedure in the pool industry for many
decades. The reactions involved have been documented and published in widely
available texts. Recently, however, a myth has been seeping into the literature
and into chemistry seminars provided to service personnel. This particular myth
is that different methods of acid application have the effect of producing
different amounts of alkalinity and pH reduction in the pool. This paper
demonstrates the fallacy of this myth.
Robert W. Lowry
Lowry Consulting
Calculations for Spa Volumes
A common difficulty in the treatment of spas lies in calculating the volume
of water contained in the vessel. The correct figure is available, of course, on
the manufacturer’s specification sheets, but they are frequently not available.
Two of the most common causes of incorrect calculations are addressed, with
methods for avoiding these errors.
Ben Powell
WaterCare, Inc.
“Interesting Questions” (opinion paper)
Many items which are accepted as fact in the swimming pool and spa industry
are, in actuality, either working hypotheses presented as fact or are downright
myth. Fortunately, this is not the case for most of the information we rely on,
but every once in a while we trip over something that is not correct. Many
purported facts are presented without experimental, or even anecdotal evidence
for their support. Often, when researching a bibliographic citation that
apparently supports a statement of fact, one finds that the citation leads only
to a prior statement of the supposed fact, presented without evidentiary
foundation. This article, along with others to follow, as readers have occasion
to point out similar items, is not intended for those satisfied with dogmatic
recitations of unsupported fact in industry publications. Rather, it intended to
invite thoughtful, documentable response to some puzzling contradictions or
oversights in the industry. This initial offering is presented for your
enjoyment by Ben Powell, and responses will be accepted in the form of letters
to the editor, short technical notes, or, if appropriate, research papers.
Doug Latta
Aqua Clear
Interference in Melamine–based Determination of Cyanuric Acid
Concentration
Testing for cyanuric acid levels in swimming pools and spas is typically
accomplished using a melamine–based turbidity test. Evidence based on experience
and experiments shows that there can be a masking, or interference in the
melamine–based test, which can cause errors of up to 70%. A method of correcting
the error while testing has been determined, and is described. Possible
directions to pursue in defining the exact nature of the interference are also
discussed.