How can you Soften Hot Tub Water? - Sutro, Inc

How can you Soften Hot Tub Water?

If you are a regular hot tub user, water hardness is something you must be aware of since it will affect the overall condition of your hot tub.

What is water hardness? 

Water hardness (also known as total hardness) is the amount of calcium and magnesium dissolved in water.  

Depending upon your geographic location, hardness can be high or low in your water. Hot tubs are especially prone to high levels of water hardness because of evaporation that causes saturation of minerals in the water.  

High levels of hardness will result in the scaling of the tub equipment. The saturation of calcium in the water will cause calcium deposits to build up on the walls and inside the circulation system. It can end up clogging the filters and the plumbing, causing them to fail. 

Water with low levels of calcium is called soft water. When water hardness falls below the optimal levels, the water becomes corrosive, and it ends up damaging the equipment made up of metal and also the interior of the hot tub shell. 

How can you measure it? 

Using pool test kits is one of the best methods to check the water's total hardness. These are very accurate but take some time and effort. A hot tub's optimal water hardness levels are between 150-250 ppm. 

For a more detailed check of your water hardness and overall water chemistry, it is best to get the water checked at a local pool store or a pool service. 

How can you soften the water? 

The best method to lower the water's hardness is to add more fresh water to the hot tub. If the levels have gone berserk and risen way above the 250 ppm mark, it is best to drain the hot tub and refill it with fresh water. 

Properly clean the hot tub to remove calcium/mineral deposits from the walls, filters, and plumbing. 

Using a hose filter to rid the water of any excess minerals while filling the tub is a great idea. If you are thinking about using water softener chemicals, that is an absolute no-go for hot tubs.

Keeping a check on the water chemistry is also essential, as levels of high alkalinity and pH reduce the ability of water to hold minerals, which results in the scaling of your hot tub equipment. You must also follow the routine maintenance procedures for the hot tub. 

How to increase hardness in the water? 

Low levels of total hardness in hot tub water indicate low pH levels, resulting in the corrosion of the equipment and sometimes a slimy feel to the water. The easiest method to raise the total hardness of water is to add a calcium hardness increaser suitable for hot tubs. 

How can you prevent hard hot tub water? 

The best method to prevent hard hot tub water is to maintain the water balance. You can also clean the hot tub walls between water changes to loosen any scaling. This way, you’ll prevent extra calcium from saturating the water and increasing the total hardness of your hot tub. 


The hardness levels of hot tub water are easy to correct. The easiest method to soften the hot tub water is to clean and refill the hot tub with new water. Maintaining optimal water hardness makes maintenance easier and keeps your hot tub working for longer. 

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