Gas heater, fiberglass jacuzzi — water hardness level?

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Hyrul

Member
Apr 5, 2025
7
Medellin Colombia
I have a fiberglass jacuzzi which is heated with a gas heater. Where I live, we have months with 20+ days of rain.

My water hardness level is essentially non existent. How important is it to get it up, given that’s it’s a fiberglass jacuzzi and gas heater?

If an increase is needed, where do you typically buy the calcium? I’ve never seen it at the local pool/hottub stores here (Medellin Colombia)

Thanks!
 
Hyrul said:
My water hardness level is essentially non existent. How important is it to get it up, given that’s it’s a fiberglass jacuzzi and gas heater?
Click to expand...

Gas heaters need around 200 ppm of calcium in the water. Direct-fired gas heaters tend to build up a thin layer of calcium carbonate on their internal surfaces over time. This thin layer acts as a barrier to physical metal erosion (from high water flow rates) and chemical attack (from chlorine). However, this film is not indestructible, and it can come and go over time depending on CH and pH levels.

Calcium Hardness - Further Reading

www.troublefreepool.com www.troublefreepool.com

This thread discusses the different types of calcium sold, including food grade. Calcium is used in plastering. Talk to a plaster company or a food ingredient supplier.

Calcium Chloride not getting hot

Anyone ever had calcium hardner not get hot? I just opened a new bag and mixed it with pool water in the same proportion i usually do, 1lb with half of a 5 gallon bucket and it didn't warm up. Also, typically after i stir for about 5 minutes the water is cloudy and this batch was clear. Any...
www.troublefreepool.com www.troublefreepool.com
 
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