Correct Level for Calcium Hardness

by Charlie

In your u-tube video from January, 2014, you state that the correct level for calcium hardness should be 150-250 ppm and that 250-500 ppm is too high.

In a word, Why is 250-500 too high?

I recently had a 20'ish year old fiberglass pool refurbished. The contractor was very specific, including some written documentation, that they wanted the hardness level to be maintained in the 350-400 ppm range. This is not a fancy pool with a heater or other accessories.

Having spent most of my adult life up North, pool water chemistry has not been a core competency for me. I'm now trying to learn how to do pool chemistry correctly. Your videos have been a tremendous help.

Thank you

Hi Charlie. This is really a huge topic so I'll be as concise as I can. First, you always want to go on the manufacture's recommendations due to warranty issues.

The reason I say to maintain the CH at 150 - 250 ppm is it's a good mid-road figure that encompasses the majority of pools. Some place such as FL and AZ have hard water, 300 ppm or greater. It's difficult to maintain a lower CH when the fill water is hard. There's no reason to add a hardness increaser, called calcium chloride, to the pool.

Next, a high CH with a maintained high pH level can precipitate calcium out. This causes scaling and rings at the water line. I did a video on that and it can be seen on YT. The water in FL is hard, so I maintain the pool's pH level between 7.2 - 7.4. It keep it on the acidic side and decreases the affects of higher CH hardness. You can see the tiles at the water line are perfect. Normal range for pH is 7.2 - 7.8, but in this situation, I'd want to keep the pH a bit lower.

Now we get into the realm of salt pools. Hard water with a high maintained pH level can cause a chlorine cell to calcify up, causing malfunctions and no FC. When you have no FC the water will go green due to the proliferation of algae spores.

I've seen first hand what can happen to cells when the water is too hard. Some fiberglass pool manufacturers tell their customers to maintain a TA of 120 - 150 ppm. Salt pools can have a TA of 60 - 80 ppm. So, what if you have a fiberglass salt pool?

A TA of 80 - 120 ppm is good for all pools. That's just an example. So that would be my answer by using the pool chemistry that I understand and have used for years.

Hope that helps and have a great Summer.


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