Cheapest Way to Increase Calcium Hardness in Pool

A low calcium hardness (low calcium levels) in your pool can cause excessive foaming in the water. It also messes up the pool’s pH which can corrode metallic parts like the pool’s railings.

Ideally, you want a calcium hardness level between 175 and 225 ppm for a vinyl or fiberglass pool and between 200 and 275 ppm for a concrete or plaster one. 

Calcium hardness should be balanced; not too less, not too much. Both deficiency and excess can cause trouble. If you are not sure about your current calcium hardness levels, you’ll need an accurate, digital pool test kit. You’ll also need to know this level to calculate how much chemical needs to be added.

Thankfully, increasing a pool’s calcium hardness is way easier than lowering it. And there are a few neat little tricks that can do that without costing a fortune. And no! A little bit of baking soda will not do that.

Cheapest Way to Increase Calcium Hardness in Pools

The cheapest way to increase calcium hardness in a pool is to add calcium chloride (CaCl2). Calcium chloride is the main active ingredient in most calcium hardness increasers and it is really cheap if you buy it from a local store or an online retailer like Amazon or Lowe’s.

For the cost breakdown, I am going to use Pool Mate calcium hardness increaser as an example. The stuff costs only 20 bucks for an 8-pound bucket, as of now, but you can check the latest price here. To raise the hardness by 40 ppm, you only need 1.8lb and 3.6lb for a 5000 and 10,000 gallon pool. Try and beat that!

Not only is calcium chloride dirt cheap, it is equally as easy to use. Just add the calcium chloride to the water and most of it will dissolve immediately if it is high-quality. To do that, mix the calcium chloride in a bucket of water in the following ratio: 2 pound in every 5 gallon bucket.

Some of the calcium chloride will settle down to the bottom of the pool. You can mix up the residue by sweeping it with a dedicated pool brush and should be no problem at all.

How Much Calcium Chloride Should You Add?

The first and foremost step for this calculation is knowing your current pool water hardness. You’ll need some sort of a test kit that can provide repeatable accurate readings. Pool Exact EZ Photometer Master is a personal recommendation but any good test kit will do.

Now that you know what the current level is, you know exactly how much you want to increase that. Just keep it above 175 ppm for a vinyl or fiberglass pool and above 200 ppm for a concrete or plaster one.

Next, use this handy table to know exactly how much calcium chloride you need to add.

Desired Increase in PPM5000 Gallons10,000 Gallons15,000 Gallons
10 ppm7.2 oz.14.4 oz.1.8 lbs.
20 ppm14.4 oz.1.8 lbs.3.6 lbs.
30 ppm1.35 lbs.2.7 lbs.5.4 lbs.
40 ppm1.8 lbs.3.6 lbs.7.2 lbs.
60 ppm2.7 lbs.5.4 lbs.10.8 lbs.
80 ppm3.6 lbs.7.2 lbs.14.4 lbs.
100 ppm4.5 lbs.9 lbs.18 lbs.

Cheap Calcium Hardness Increasers

Most calcium hardness increasers cost between $2.5 and $4 per pound. Here are a few economical calcium hardness increasers that work really well and are equally high quality:

  1. Pool Mate Calcium Hardness Increaser
  2. Robelle Calcium Increaser 
  3. Clorox Pool&Spa Calcium Hardness Increaser

Pool Mate Calcium Hardness Increaser


  • Economical
  • Amazon Prime shipping 
  • Thin flakes
  • Dissolves easily


  • Needs to be mixed up

The Pool Mate Calcium Hardness Increaser is no bull-shit, straight to the point hero for your pool. It rapidly increases your pool water’s hardness without any drama.

The flakes are thin which means it dissolves easily. By the time it reaches the bottom of the pool, most of it has already disappeared and dissolved. The residue can be mixed with one sweep of a dedicated pool brush. 

It comes in different sized packages of 4,8,16 and 25lbs to serve your needs and the packaging is entirely eco-friendly. The manufacturer recommends mixing it up before pouring in into the pool to prevent clumping.

Robelle Calcium Increaser 


  • Dissolves rapidly
  • Prevents corrosion
  • Economical


  • Needs to be mixed up

Robelle’s calcium increaser is an Amazon’s Choice product for calcium increasers. Priced similar to Pool Mate’s alternative, this one is also very economical. The cost per pound is slightly less than $3 if you buy a 25-pound bucket.

The high quality manufacturing allows easy mixing which not only prevents wastage but also protect your pool from looking like a mess. Most of the mixture will dissolve even before it reaches the pool’s floor.

This calcium increaser also require to be mixed beforehand which does limit the ease of use.

Clorox Pool&Spa Calcium Hardness Increaser


  • Recognized brand
  • Economical
  • Comes with an app


  • Gets very hot

Clorox is a household name for most American homes and there is a reason for that. They provide no-nonsense, cheap and reliable solutions to all the home supply requirements.

Clorox makes your life even easier by providing an app that allows you to calculate the chemical requirements and guides the whole process.

Just a word of caution: it gets a little hot upon mixing with water so it might be best to just spread it out on the surface of your pool rather than mixing it beforehand.

Costing just 10 bucks for a 4-pound bag, as of today, Clorox beats everyone on the list in terms of value. For the latest price, please click here.

Is Baking Soda a Cheap Way to Increase Calcium Hardness?

No, baking soda is not at all effective in increasing calcium hardness. It merely increases the pool’s pH and has no effect on the hardness of water. One of the many myths surrounding pool care!

In fact, adding baking soda after adding calcium chloride can wreak havoc and cause excessive clouding and is strictly not recommended. I have given some tips to cure clouding in my article about what to do if you have added too much clarifier.

If you were looking for the cheapest way to chlorinate a pool, we’ve got you covered there too.

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