How to Treat Calcium Hardness in Hot Tubs

How to Treat Calcium Hardness in Hot Tubs

Don’t let chemical imbalance damage your hot tub. You can easily resolve this problem by following these simple steps:

What is calcium hardness?
Calcium Hardness, sometimes referred to as Total Hardness, is basically the measure of the amount of calcium and magnesium dissolved in the water in your hot tub. These chemicals are found everywhere including our water supply, meaning that where there is water, there will be calcium. The key is exactly how much calcium is in your water.

Ideal level
So what exactly is the normal range for calcium hardness in a hot tub? In general, the recommended range for calcium hardness is between 175 and 275 parts per million (PPM), with anything below 150 PPM being considered very low and anything above 1,000 PPM considered very high. This, of course, can vary depending on the type of hot tub you have and the chemicals you use in the water. I recommend that you check with your hot tub manufacturer to determine the ideal calcium levels for your specific hot tub. Source: SwimUniversity

Test the water
If the level is too low or too high from the recommended figure, then adjustment can be done appropriately. Use a test strip reader to get the level of water’s calcium hardness. Source: DoItYourself

Put chemicals in
Measure out 1 1/2 oz. of trisodium phosphate for every 1,000 gallons of water in the hot tub to lower the calcium hardness by 11 ppm. Pour in the trisodium phosphate as you walk around the hot tub. If you don’t have trisodium phosphate, continue to step 3.

Drain the hot tub
Open the drain plug underneath the hot tub to remove at least 6 inches of water if you don’t want to add trisodium phosphate to lower the calcium hardness. Monitor how much water is removed and replace the drain plug when you have removed 6 inches of water.

Refill the tub
Attach the garden hose to the water faucet. Turn on the water and replace the water removed from the spa. Source: Hunker

Need help on maintaining your hot tub? We’ve got you! Take a look at our shop for high quality chemicals guaranteed to solve your hot tub problems.


Universal Spas
19300 Langley Bypass, Surrey, BC V3S 7R2
(604) 539-2182

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