Is There Any Substitute for Calcium Hardness Increaser?

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Calcium hardness increaser is a chemical that is used to raise the water hardness in pools and hot tubs. It is available from pool stores under various brands, but the active ingredient is always in one of two forms: calcium chloride and calcium chloride dihydrate.

There are many other household uses for calcium chloride beyond pool and spa care, from fish-keeping to home brewing to molecular gastronomy. But is it possible to substitute any other version for use in your pool or hot tub? And is it a way to potentially save some money?

Calcium hardness increaser and its purpose in pools and hot tubs

Calcium hardness increaser is a chemical used to raise the calcium hardness level in pools and hot tubs. This is important because the correct calcium hardness level helps to prevent scaling and corrosion, and it also makes the water feel softer.

There are a number of different brands of calcium hardness increaser, and the amount that you need to add will depend on the size of your pool or hot tub. Most products come with instructions on how to properly add the chemical to your water.

If you live in an area with soft water, you may need to add a significant amount of calcium hardness increaser to your pool or hot tub to get it up to acceptable levels. This is when buying in bulk for better discounts starts to seem attractive.

There are two main types of calcium hardness increaser: calcium chloride and calcium chloride dihydrate

Calcium chloride is the most common type of calcium hardness increaser, and it is typically sold in granular or flake form. Calcium chloride dihydrate is another type of calcium hardness increaser, and it is typically sold in powder form.

The key difference between calcium chloride and calcium chloride dihydrate is that calcium chloride is anhydrous, which means it doesn't have any water, while calcium chloride dihydrate has water molecules.

Both kinds of increaser are effective at increasing the hardness of water.

Why use a calcium hardness increaser substitute in place of traditional calcium hardness increaser?

There are a couple of reasons why you might want to use a calcium hardness increaser substitute in place of traditional calcium hardness increaser:

  • First, substitutes are often cheaper and more readily available.
  • Second, you might have simply run out of your regular version, and be wondering if you can use something else around the house in a pinch.

This is true of many spa and pool chemicals, such as using baking soda to raise pH and total alkalinity, or bleach as a chlorine shock. But what about increasing hardness?

What are some possible substitutes for calcium hardness increaser?

The main form of calcium chloride you may have around at home is in the form of a de-icer.

These types of calcium chloride flakes or pellets, by brands like DowFlake and Peladow, are sold to melt snow on your driveway. They are usually a similar purity (around 94%) as that sold as calcium hardness increaser by pool and spa care brands.

In some cases it can be cheaper, but not always, so it's worth shopping around. Often, you can get much larger quantities for around the same price. Compare this 25-lbs bag sold as a pool and spa product from Pool Mate:

Pool Mate 1-2825B Pool Calcium Increaser, 25-Pounds (Bag)
Pool Mate 1-2825B Pool Calcium Increaser, 25-Pounds (Bag)
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And this 50-lbs bag sold as an ice melter from Snow Joe:

Snow Joe AZ-50-CCP Melt-2-Go 94% Pure Calcium Chloride Pellet Ice Melter, 50-lb Resealable Bag
Snow Joe AZ-50-CCP Melt-2-Go 94% Pure Calcium Chloride Pellet Ice Melter, 50-lb Resealable Bag
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The pros and cons of using de-icer as a substitute for calcium hardness increaser

De-icer can be an effective substitute for calcium hardness increaser in a pinch, but it also comes with a few potential drawbacks:

  • The pellets are usually large as they're designed to stick around to melt snow for as long as possible, whereas you want something that will dissolve as fast as possible in your pool or spa.
  • It can be hard to tell the exact purity of each brand, and therefore to know with certainty whether it will be suitable.
  • Additionally, de-icer can be more expensive than calcium hardness increaser, and come in larger quantities than you need.
  • Measurements can be tricky and involve some trial and error, as the packages are not going to give you the information you need to calculate how much to use in your pool or hot tub.

Before using de-icer as a substitute for calcium hardness increaser, be sure to weigh the pros and cons to decide if it's the right choice for your needs. If you don't live in an area with very soft water, you may just never need large enough quantities for it to be worth looking for a substitute.

For example, this 4-lbs bag from Clorox is certainly going to last most spa owners a good amount of time:

Clorox Pool&Spa 12204CLX Calcium Hardness Increaser, 4 lb, White
Clorox Pool&Spa 12204CLX Calcium Hardness Increaser, 4 lb, White
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Closing thoughts

The main substitute for calcium hardness increaser you might have at home is calcium chloride in the form of a de-icer.

While this can be used to raise the calcium hardness in your pool or spa in a pinch, there are also some drawbacks to be aware of.

If you're at all unsure, it's usually going to be safest to just order a pool-specific version of calcium hardness increaser and wait the extra few days for it to arrive.

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