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50-55 WATER TESTING:SPN Master pages 12/9/08 22:58 Page 5
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THE THREE MAJOR WATER
QUALITY “TESTS”
pH
pHisameasureofhowacidicorbasicthe
wateris. pHhasascalefrom0-14,with7
beingneutral. Below7andasubstanceis
definedasbeingacidic,whilelevelsabove7
aresaidtobebasicoralkaline. Everything
thatentersapoolhasapHvalue.Tohave
pH in balance we adjust the water with
additionsofpHincreasers(bases)orpHde-
creasers(acids)toachievetherangeof7.2-
7.8. IfwatershowsapHvaluebelow7.2the
waterisinacorrosive(acidic)conditionand
youwillneedtoaddabasetobringthepH
into a more basic range to prevent
corrosion. IfthepHisabove7.8,wearein
ascaling(basic)conditionandmustaddan
acidtobringdownthepHtopreventthe
formationofscale.
TOTAL ALKALINITY
AclosecousinofpH,thelevelofalkalinity
in the water is a measurement of all
carbonates, bicarbonates, hydroxides,
andotheralkalinesubstancesfoundinthe
Exeterpoolintroubleoverwatertestingmethods
poolwater. pHisalkalinedependent;that The extent of the problems at a city pool where swimmers were complaining that the
is,alkalinityisdefinedastheabilityofthe water quality was causing health problems have been revealed after a report by PWTAG.
watertoresistchangesinpH. Alsoknown The Pure Water Trade Advisory Group. revealed that management at the Pyramids
as the buffering capacity of the water, pool in Exeter took inaccurate readings and left chlorine to stay at unacceptable levels.
alkalinity keeps the pH from “bouncing” The report was commissioned after Exeter City Swimming Club complained that the
allovertheplace. Lowalkalinityisraised water at the pool was causing health problems for members.
by the addition of a base (similar to pH); Report author Ian Nicks highlighted :
sodium bicarbonate is commonly used. • Inaccurate water test readings by staff, consistently rounded to the nearest half-number.
Highlevelsofalkalinityareloweredbythe • Fears that combined chlorine may have been allowed to remain at unacceptable
additionofanacid(similartopH). Experts levels, which some research suggests could affect asthmatics.
recommend“pooling”theacidinasmall • Concern over the freshness of the water with staff using a hose to top up the pool,
areaoflowcurrentforagreatereffecton which is not in line with current guidelines.
alkalinity. Thatis,addinganacidwilllower
both pH and alkalinity. Levels should be The report states: “It is unfortunate that it is clear many tests were suspect in as much as
testedweekly. there was evidence of not recording the actual chlorine levels but rounding them to the
nearest half-number and this was consistent.”
CALCIUM HARDNESS It reveals that when an electronic kit was used instead of a manual one after the
When we speak of scale, we are talking swimming club’s complaints, the results of combined chlorine rose because readings
about calcium carbonate which has come were more accurate.
out of solution and deposited itself on Mr Nicks praised the swimming club for the “very professional approach” it used to
surfaces. Itisacombinationofcarbonate gather information on the pool. The club maintained its tests showed high levels of the
ions,apartoftotalalkalinityandcalcium, by-products of chlorination, known as chloramine.
andapartoftheCalciumHardnesslevel. Mr Nicks said: “There was clear documented evidence of the witnessing of chemicals
ThetestforCalciumHardnessisameasure being added to the pool manually just before training sessions. This evidence is
of how “hard” or “soft” the water is worrying given the perceived problems in the pool.”
testing. “Hard”watercanhavehighlevels The report reveals turnover of water at the pool was carried out after more than four
ofcalciumandmagnesium. Iftheselevels hours, which is not in line with current recommendations.
aretoohighthewaterbecomessaturated Mr Nicks said it was “surprising” that a different disinfectant was not used in the pool
and will throw off excess particles out of and he said the filters were being backwashed “more than recommended”.
solution which then seeks to deposit He carried out more tests in June and said improvements in the operation of the pool
themselves on almost any surface inside had been made.
thepool. Thisiscalciumcarbonatescale;a He said more rigorous testing was now being carried out on the water and while
“white-ish,” crystallised rough spot. If the readings were “not ideal” they did comply with current recommendations.
levels are too low, the water is under- Cllr Kevin Mitchell, lead councillor for environment and leisure, said the authority was
saturated. If under-saturated, the water working on finding a replacement for the Pyramids.
will become aggressive as it attempts to He said: “We are pleased Mr Nicks has been able to satisfy himself the water is as
obtain the calcium it needs. Such “soft- good as it can be. We appreciate this is an old pool, and DC Leisure, our contractor, has
water”willactuallycorrodesurfacesinside to work hard to ensure it meets water quality standards. That is partly why we as a
the pool which contain calcium and other council are working on a project to replace the Pyramids operation.”
mineralstomaintainitshardnessdemand. The club revealed how members were suffering from wheezing, coughing and rashes
Recommendedrangeforcalciumhardness when using the pool.
is 200-400ppm. Calcium Hardness levels A spokesman said: “Swimmers, coaches and parents have all noticed a significant
shouldbetestedweekly. improvement in the atmosphere and swimming conditions at Pyramids.”
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OCTOBER 08 swimming pool news 55
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