Swimming Pool Chemical Langlier Index Chart from Adelaide Australia

by Victor K. de Fontenay

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WATER BALANCE CHARTS

MY SUGGESTIONS
Learn more yourself about looking after your pool, don't rely on the "Free Water Tests" from the pool shop unless you have them do the test & then take the results home & check them against the following:
Langlier Index Chart Table Representation yourself.

It is not hard to read the chart & using the accompanying dosage charts, You can decide for yourself if & what chemicals are needed.

INSTRUCTIONS:

I have given options for balanced water at two pH levels, 7.5 & 7.7 this is because the 7.5 is the optimum level & the 7.7 is the best obtainable level which some people can hold in hard water areas & areas effected by wind blown High pH pollutants.

If you have a Total Alkalinity of 70ppm & a pH of 7.5 then the optimum Calcium Hardness level for your pool is 375ppm.
If your pH is 7.7 the the optimum CH level is 240ppm.

These tables can be used in reverse as many times the Calcuim Hardness level is controlled by the makeup water. If your CH level is 500 & you can hold your pH at only 7.7 then keep your TA down to 50ppm.

GO TO END OF CHART FOR MORE NOTES.

Langlier Index Chart Table

pH 7.5

pH 7.7

Total Alkalinity	Calcium Hardness	Total Alkalinity	Calcium Hardness
30	900	30	750
40	700	40	400
50	500	50	325
60	425	60	260
70	375	70	240
80	325	80	200
90	280	90	180
100	250	100	160
125	200	125	125
150	170	150	110
200	125	200	80
250	100	250	65
300	85	300	52
400	65	400	45

POSSIBLE SITUATION NO1:
You find that you have a ph of 7.7 & a CH of 250 & your TA is 100. You possibly have trouble keeping your water crystal clear.
It would be preferable to lower your TA to 60.
If your pool is 60,000 litres then go to the following charts DOSAGE CHARTS & look for the one which says to Lower TA using Liquid Pool Acid. You know you have to drop from 100 to 60 or 40ppm.
Pick the 40ppm line & the 60,000 line & it will give you a figure of 3.84 Litres of Acid to bring the pH to its correct level.

This can be added over two to three days by adding the liquid acid to a bucket half full of water & then pouring the water in to the pool while the pump is running, preferably keep the pump running for 4-6 hours afterwards.

More situations will be available on a page directed from here shortly.

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REMEMBER 50% of pool water problems are Mechanical.

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