Alkalinity and Water Hardness

It is important to keep the total alkalinity at the right level. Together, the ideal levels of alkalinity, hardness and pH will ensure that the disinfection chemicals or process are working correctly.
The total alkalinity should be checked first unless the pH is far below 7.0. add pHplus to raise the pH to at least 7.2.  Calcium hardness is a measure of how hard or soft the water is. Hardness that is too low will erode the pool metal and plastering, and hardness that is too high will cause scale and make the water cloudy. Check the alkalinity and hardness from testers available from SwimmingPoolsThailand.

ALKALINITY
The ideal level should be within 80-120 ppm. Both too high and too low alkalinity can severely damage the grout, and then when the water works it way through the grout to behind the tiles, it will dissolve the tile adhesive.
Loose and broken tiles are a sign of regular inconsistency of alkalinity.
It takes time to adjust the alkalinity. Once you achieve a regular chemical balance after weekly testing, your TA level should stay relatively constant.
Low Alkalinity can be corrected by adding Sodium Bicarbonate (baking soda) to raise the TA level. Total alkalinity (TA)  is increased with sodium bicarbonate. TA. Add small amounts sodium bicarbonate or pHminus every four days until the correct TA and pH value has been reached.See
High Total Alkalinity
● makes the pH difficult to adjust and the result can be one or more of the following:
● pH value difficult to adjust
● Cloudy, murky water
● Lime precipitation
● Red eyes
●Skin irritations
To reduce the TA is a long process and can take several weeks. Add small amounts pHminus every four days until the level is correct.
Note: Make sure you follow the instructions on your brand of pHminus. Whatever their brand name, most granular or powder pHminus is sodium bisulfate. If the pool requires more than this, add the maximum amount then retest 12 hours later and make further adjustments.
Make sure to know the size of your pool, specifically the volume, as this value is required to know how much chemical to add to your swimming pool. As for the total alkalinity range, you ideally want to be in the middle of the range: 80-120 ppm (parts-per-million)
The pH level is harder to control in a pool with high alkalinity, as the buffering ability of the water to resist changes in  acidity is so high, that attempting to adjust the pH requires greater amounts of chemicals.

If your total alkalinity is too high, you may have added too much sodium bicarbonate.  Try adding a smaller amount and wait from 6 to 24 hours then test again  Adding chemicals in smaller increments can help prevent adding too much.
The local water source may be the cause of high alkalinity, as city water supplies often have a higher alkaline water level to prevent corrosion in pipes and sewer lines.   So you might expect the alkalinity to rise on its own as you top up the water lost from backwashing and evaporation.
Decrease total alkalinity with sodium bisulfate (dry acid)
 
Sodium bisulfate, also called dry acid, can be used to reduce pool water total alkalinity.
1. Test the swimming pool total alkalinity level.Make sure you have tested your pool total alkalinity.
2. Turn off the pool pump and wait one hour to let the pool circulation stop.
3. If your level is above 120 ppm, then you need to lower the level to about 100 ppm. Read the label on the back of the product package to determine how much to add.  Sodium bisulfate is typically 93.2% pure, so make sure you find this percentage on the package.
4. Dilute.Dilute the dry acid in a bucket of water. Make sure the substance is completely dissolved.
5. Add to the pool water.At the deep end of the pool, pour the diluted dry acid into the water, making sure to keep the stream as narrow as possible. You want the stream to penetrate the upper area of water and get as deep as possible.  This helps to avoid disrupting the pH level in the water.
6. Let the pool sit.Leave the pool to stand still for one hour.  After one hour turn the pool pump back on.
7. Test the pool water. Retest the total alkalinity level after six hours, but before 24 hours after you have added the dry acid mixture.


8. Repeat if necessary. Dilute and add more dry acid if you need to bring your level down a little more, but wait at two to three days before adding more, as the total alkalinity may still drop somewhat.


Conclusion
Keeping total alkalinity in balance is one of the important three water balancing steps.  You need to know how to test your total alkalinity, and how to lower the level if it is too high.  You also need to know which chemicals are available to lower total alkalinity, and how much to add based on your pool size and how much you are over.[1]

Salt water pools: Just like any pool, you need to pay close attention to pH, Alkalinity, Calcium Hardness and Cyanuric Acid (stabilizer) levels in the pool. Chlorine-tablet treated pools tend to gravitate towards the low end of the pH and Alkalinity scale, while salt water pools tend to slowly rise in pH level, requiring pH reducer. Salt water pools are most stable with a pH of 7.2, and Alkalinity of 70-80 ppm. A stabilizer level of 50-80 ppm is recommended by most salt system manufacturers. High calcium hardness levels have no effect on salt water pools, but a level of 180-200 ppm may result in less scale on the salt cell plates.

CALCIUM HARDNESS
Calcium hardness defines how hard or soft your pool water is by measuring its dissolved calcium:water ratio. Hardness that is too low will erode your pool's metal and plastering, while too much hardness will create a breeding ground for the growth of scale and cloudy water.

Ideal calcium hardness levels are  200 – 400 ppm . The right level of calcium hardness level is essential for the best water quality and avoiding  the  water damaging the pool equipment or causing limescale to build up on the walls, floor, and fixtures and fittings.

Calcium hardness does not need to be checked quite as often as  the pH, chlorine, and  and alkalinity. Generally once every one or two weeks is sufficient.
Water Too Hard
: If your water has become too hard, it can result in cloudy pool water that you just can’t seem to clear up . At the same time, it can also lead to the build-up of calcium sediments on the sides of your pool and even inside the plumbing of your pool.
Water Too Soft
: If the water is too soft can severely damage the grout, and then the tile adhesive in your pool when the water works it way through the grout to behind the tiles.
Loose and broken tiles are a sign of regular inconsistency of alkalinity.
If the hardness is below 200 ppm in your pool, the water will become corrosive. When it does, it can begin to dissolve the concrete and begin to corrode metal in your pool resulting in potentially expensive pool repairs down the road.

Balancing Water Hardness

1. Clean the pool thoroughly before testing for hardness. 
1. Ensure the pH and alkalinity levels are correct
1. If the water hardness level is above 400 ppm, lower the calcium hardness level. If it is below 200 ppm, raise it.

Raising Calcium Hardness
Raising hardness levels is often much easier than lowering the levels. To raise the hardness levels, simply add  https://swimmingpoolsthailand.com/en/258-calcium-chloride to your pool. Follow the instructions on the package carefully for the size of your pool in order to obtain the best results.


Lowering Calcium Hardness


1. Drain some of the water from your pool and replace it with  softer water.
2. If replacing the water isn’t an option, you can use a flocculant to attract the excess calcium and cause it to clump. After you use the flocculant, clean the walls and floors of your pool to remove the excess calcium and then backwash and clean your pump filter.
3. If none of these options work, you can also try adding pHminus to raise the saturation levels. While this won’t reduce the hardness of your water, the rise in saturation levels will bring your water back into balance.
4. If all else fails, you may need to invest in water softening equipment.

[1]  Pool & Spa Water Chemistry, A Testing and Treatment Guide, Waterproof Edition, 2005. Taylor”