What is Total Alkalinity and Total Hardness?

What is Total Alkalinity and Total Hardness?

Maintaining balanced pool and hot tub water requires a lot of attention and education about the different chemicals and their importance in keeping water safe for swimming. pool or hot tub owners (or future owners) will hear a lot about “total alkalinity” and “total hardness”, two key factors that affect water chemistry

But why are they important? The pHin experts break it down:

What is Total Alkalinity?

Total Alkalinity is the total concentration of dissolved carbonates, bicarbonates, hydroxides and cyanurates present in the water.

Alkalinity acts as a pH buffer in pools and hot tubs, adding a layer of armor that absorbs fluctuations and keeps your pool chemistry stable. Water with a high alkalinity level can decrease the water’s acidity causing cloudiness, lime precipitation, calcium deposits, and make adjusting pH more difficult.

How to Manage Total Alkalinity

Test the total alkalinity of your pool once per week. If the alkalinity is high, read the instructions on your chemical of choice (sodium bisulphate or muriatic acid) and carefully and measure it out. If alkalinity is low, there are two ways to increase the level: sodium bicarbonate (baking soda) or any type of alkalinity increaser product -- be sure to purchase a product made from sodium bicarbonate. When distributing chemicals, add the increaser or decreaser in either the deep end of your pool or where the water return distributes.

These chemicals can cause irritation, so don’t touch the water for at least six hours. Then, retest the pool’s total alkalinity; if it’s still too high or low, re-treat the water again as needed and continue that process every six hours.

What is Total Hardness?

Total hardness refers to how much calcium is dissolved in the water. The level of hardness should be maintained between 200 and 400 ppm.

Water hardness varies based on region, so, if your water is regularly hard then you’ll have to drain your pool once or twice a year. Fresh water can then be added to get the water back in balance. A hardness reducer can also be used to soften water levels.

How to Manage Total Hardness

If your calcium hardness is above 400 ppm, you’ll need to drain a portion of your pool or hot tub and add fresh water. This helps to lower levels because calcium-rich water is pumped out and replaced with tap water during the refill. If your calcium hardness is too low, it can be increased by adding calcium chloride from your local pool retailer. If you want to take the hassle out of pool and hot tub care, consider pHin. It floats in the water and keeps an eye on pH, sanitizer, and temperature (more than 1000x/week!) as well as total hardness, total alkalinity, and cyanuric acid. With the app, it sends alerts whenever your water needs balancing so you’re always ready for safe swimming.

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