Why is Calcium Hardness Important in Swimming Pools?

As a swimming pool owner, one of the things you need to understand to keep your pool running well is the calcium hardness levels in the pool water. The mineral calcium naturally exists in water, but it needs to be managed so it doesn’t get too high or low, causing problems.

You have probably heard the terms hard and soft water before. Hard water refers to a large amount of minerals present in water. Calcium hardness, therefore, refers to the level of calcium carbonate present in your swimming pool water. Maintaining the right level of calcium hardness in your pool is important for the overall balance of chemicals in the water. Calcium hardness levels should range between 200 and 400 ppm. As long as the level remains in this range, your water chemistry should be correctly balanced.

What happens if the calcium hardness level is out of this range? What problems will I notice? What can I do to fix these problems if I find them?

High CH Levels

If calcium hardness levels are too high, you will start to notice scaly formations in the water, as the mineral builds up. The pool surface also becomes rough and scratchy. The filters may become clogged, and the water can therefore begin to look cloudy. All these conditions will probably lead to swimmers complaining about their eyes and skin being irritated by the water.

If you experience this problem, you will need to make the necessary adjustments to lower alkalinity and pH levels in the water. If the problem is big enough, you’ll need to at least partially drain your pool, and add new water. It’s important, however, that the new water not have a high level of calcium. This may require allowing the new water to pass through a water softener before adding it to the pool. If you heat your pool, pay close attention to CH levels going up because high heat can cause these levels to rise.

Low CH Levels

If the calcium hardness level drops too low, you will be faced with harsh, corrosive water. The biggest problem with this corrosive water is damage to your pool surfaces, such as etching, pitting or stains on the walls. If left untreated, it can also cause your pool systems to fail.

If you notice this happening, you will need to add a chemical called calcium chloride to the water. It is important to thoroughly understand how to do so, however, because calcium chloride can emit a great amount of heat when it is added to the water. It is also important to understand the proper amount and strength to add. It’s a good idea to get professional help if you feel concerned about correctly using this chemical and getting your pool water properly balanced.

The most important thing you can do is to keep careful watch on the levels of calcium hardness in your pool. Regular monitoring can help you catch a problem early on and prevent you from having a big problem down the road.