The Cheapest Way to Increase Calcium Hardness in a Pool
The absolute cheapest way to increase the calcium hardness of your pool is by adding calcium chloride (CaCl2). This is a very cheap chemical you can find at your local pool store that will increase your pool’s calcium levels quickly and easily.
It usually costs between $3-$4 per pound and comes in two strengths: hydrated (77%) and anhydrous (100%). You shouldn’t need the branded stuff either – any shop-bought calcium chloride will do.
If you can’t find any calcium chloride, some standard shop-bought decier will do as well! These can actually be cheaper than calcium chloride, but they don’t always dissolve the best!
Near the bottom of this article, I will make a few recommendations for products based on mine and others’ experiences.
Important Step: Don’t forget to test your calcium hardness levels before purchasing calcium chloride and putting it in your pool! I also made a guide on my favorite testing kits if you want equipment recommendations.
How to Add Calcium Chloride to Your Pool Safely
To increase your calcium hardness with CaCl2 by 10 ppm, add around 1 1/4 lbs for every 10,000 gallons of water. If you’re working in oz, add 2oz of calcium chloride for every 1,000 gallons of water to increase the hardness by 10 ppm.
Continue adding calcium chloride until your pool is between 150pmm and 250ppm. I always found 200 ppm was a good number to aim for.
Quick Note: You shouldn’t need to add much calcium chloride if you have a fiberglass or vinyl pool – a reading of 100-200ppm is usually fine. The above figure of 150-250pmm only applies to concrete, plaster, and pebbletec pool designs.
Make sure to broadcast the calcium evenly around the perimeter of your pool. Avoid pre-mixing it with water in a bucket as this can produce vapor, potentially causing some nasty burns! This is also why you should always wear protective gear when you’re using chemicals in your pool.
The calcium chloride will take some time to dissolve – it doesn’t happen straight away. Due to the heat reaction that can occur as well, give it some time before you go jumping in.
If there’s any undissolved residue at the bottom of the pool, give it a swirl with a pool brush and it will quickly disappear.
Make sure your pool pump is on during this whole process. You’ll want the calcium chloride to work its way around your pump and filter, and circulate effectively.
How to Maintain a Balanced Calcium Hardness Level
The simplest way to maintain the calcium hardness in your pool is by testing the water and correcting any imbalances.
Testing the calcium hardness every one to three months will do the trick. Just make sure to schedule them so you don’t forget. If left, you will quickly notice the signs of hard or soft water damage. Sorting the issue quickly will prevent any expensive issues/cleaning.
Balancing calcium hardness will depend on which way the levels are going:
- If hardness is decreasing, simply add in some calcium chloride as detailed above
- If hardness is increasing, you can either partially drain the pool and add fresh water or add muriatic acid to lower PH and alkalinity (preventing scaling)
Are There Any Cheaper Alternatives to Calcium Chloride?
Not really, there are alternatives but they’re similar in price and lead to more headaches than they’re worth.
Deicer
The most common one I’ve come across is de-icer pellets/flakes – the stuff you scatter on your driveway after heavy snowfall. These can be cheaper than calcium hardness increasers and are similar in calcium purity, but they’re quite inconvenient if you want to use them in a pool.
This is because:
- The pellets are larger and take longer to dissolve
- Measuring how much you need is tough as there aren’t exact measurements on the back of the packaging. (You can always use the measurements I’ve provided above, however).
- They can be more expensive – it varies by brand
I wouldn’t recommend using de-icer as a way to increase calcium hardness, but it is an option. Sticking with the old faithful is usually the best way to go when you’re messing with pool chemistry.
Cal-Hypo
You can also use calcium hypochlorite (cal-hypo) as another alternative chemical you can use to increase calcium hardness. I’ve heard of some pool owners who use it to slightly increase their pool hardness. However, it isn’t as effective as the other options mentioned on this list.
This is because it is mainly used as a shocking agent because it introduces chlorine in your pool. For every 10ppm of chlorine, it will add around 7ppm of calcium. Therefore, you’ll pump your chlorine numbers sky-high if you use this as a calcium hardness increaser. So, prepare for stinging eyes!
What About Baking Soda?
Baking soda is not an effective method to increase calcium hardness in a swimming pool. This is a common myth I come across all the time in pool chemistry.
What baking soda is good for is increasing overall alkalinity in a pool. If you need to rebalance PH and alkalinity levels, this is an option that’s open to you.
Avoid using baking soda as a calcium increaser and don’t throw any in your pool if you’ve just used calcium chloride – it will turn your pool cloudy!
My Recommended Calcium Hardness Increasers
Below, I’ll list a few calcium hardness increaser products that have been tried and tested throughout the years. They’re affordable, high-quality, and do the job without any BS.
Puri Tech Calcium Hardness Increaser (My Go-To)
This is one I’ve used throughout my career. It’s affordable and dissolves incredibly quickly. I have had a few batches that looked a little lumpy, but once I added it to the pool it took about 30 seconds to dissolve. If there was any residue at the bottom of the pool, I’d just use a pool brush and keep it a swirl.
It’s simple, no fuss, and you can get this easily off Amazon here with free delivery.
I would, however, recommend you put this into a spare container or bucket when you open it. The bag it comes in is a little flimsy and can be a pain to maneuver.
Pool Mate Calcium Hardness Increaser (Third-Party Recommendation)
One I’ve been recommended a lot is Pool Mate’s calcium hardness increaser. I have used it a few times and, like Puri Tech, dissolves quickly. I noticed the flakes are thinner in this product, so I’m curious if it’s actually quicker than the Puri Tech.
One thing I do like about this product is the variety of sizes. You can get this in as little as 8 lbs or as much as 50 lbs. So, there is something to suit your needs. You can also get this in a bucket – so you don’t have the same storage issues you get with the Puri Tech.
You can find it on Amazon here with free delivery.