What is Alkalinity and should I be worried about it in my Pool or Hot Tub?

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What is Alkalinity and should I be worried about it in my Pool or Hot Tub?

With all pools or hot tubs, one of the most important jobs is making sure that your water is regularly tested and safe to use. There are a number of parameters that can be measured including the disinfectant levels (usually chlorine or bromine), pH and alkalinity.

What is Alkalinity?

Alkalinity, normally referred to as total alkalinity, is the measurement of the alkaline salts (carbonates, bicarbonates) within the water and is expressed in ppm or mg/l. Alkalinity also gives an indication of the water-resistance to change as the higher the level the greater the buffering capacity of the water. Pure water has very little buffering capacity so is susceptible to wild changes in pH when chemicals are added. This can lead to what is sometimes referred to as ‘pH bounce’ and the pH becomes difficult to control. If the levels are too high then the pH can ‘lock’ and become difficult to move.

What level should you be looking for?

To avoid pH bounce or lock you should be looking at a total alkalinity level of no less than 80ppm and no higher than 160ppm. The lower limit is also important as not only can this result in pH bounce but also some flocculants and clarifiers do not operate correctly below 80ppm. Commercial alkalinity increasers are available if the level does need to be raised. Reducing alkalinity levels is a little trickier.

How do I test for alkalinity?

There are various simple tablet count or speed test kits available to measure total alkalinity. These are easy to use, work on proven chemistries and give accurate and repeatable readings. Alkalinity can also be measured on electronic devices such as the Scuba II Electronic PoolTester – these give the readings in a clear digital format so are easier to read.

Should I be worried about total alkalinity?

Yes, you should know your total alkalinity level. But you should know all your pool levels otherwise how do you know the water is safe. You should be testing regularly throughout the day especially in a hot tub as conditions can change quickly due to the relatively small volume of water. The water should ALWAYS be checked before the first use of any day. Poor water can cause serious issues.

With regard to alkalinity, every effort should be made to keep the readings between 80-160ppm if possible. However, it does depend on the alkalinity level of the incoming water. In some areas of the UK the alkalinity of mains water is extremely high. As mentioned above reducing the levels can be tricky and if you start adding chemicals then you can end up changing the alkalinity whilst at the same time making the chlorine and pH levels incorrect. Having the correct pH and disinfectant levels is important safety-wise so don’t threaten these by chasing alkalinity. If levels are high but the water looks good, is safe and is correctly pHed then monitor the readings but don’t add additional chemicals for no reason.

So should I be worried?

You should know the levels, you should monitor the levels, and you should adjust the levels if there are issues - but do not chase levels to the detriment of other parameters. Above all make sure you have a suitable, accurate testing kit.

Alkalinity Testing Options from Lovibond

For more information on pool and hot tub alkalinity testing from Lovibond please view the following:

DescriptionCodeMeasures Suitable for
Domestic PoolTesters & Hot Tubs Kits    
5in1 Multi PoolTester151900Cl 0.1-3mg/l
Cya 20-200mg/l
TA 20-800mg/l
CaH 20-800mg/l
hot tubs
Tablet Refill Pack 5in1 PoolTester515980  1515900
Electronic PoolTester Scuba II216100-17Cl 0-6mg/l
Br 0-13.5mg/l
pH 6.8-8.4
Cya 1-160mg/l
TA 0-300mg/l
hot tubs
Professional Instruments    
MD100 3in1 Photometer278060Cl/pH/Alk pools
hot tubs
MD100 6in1 Photometer278091Cl/pH/Br/Cya/TA/CaH  
MD110 6in1 Photometer2980902Cl/pH/Br/Cya/TA/CaH With Bluetooth

Pool and hot tubs alkalinity testing systems from Lovibond.
Abbreviations used: Br = Bromine, CaH = Calcium Hardness, Cl = Chlorine Cya = Cyanuric Acid, TA = Total Alkalinity

For further information on regulations and legislation please use the following links:

Camlab can supply a comprehensive range of test kits for swimming pool and hot tub testing. Please contact us for further information.

This blog article was supplied by the technical department at Lovibond.

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Alkalinity is the measure of the compounds in a pool or hot tub, specifically, the amount of calcium and magnesium. The more Alkalinity your pool has, the less likely the pool is to become cloudy.