Definition:
Total alkalinity measures how many alkaline substances are in your pool water. When pH is unbalanced, it’s usually tied to a wonky alkaline reading.
Why does total alkalinity matter?
Your pool’s pH swings back and forth based on a number of factors, and alkaline substances help your water stay stable. Here’s why: the ionic compounds that make up alkaline substances do the heavy lifting. They act as a buffer against sudden changes in acidity and alkalinity. The end result is a balanced pool.
You want your total alkalinity to be 80 to 120 parts per million (ppm). Anything higher, and you’ll likely be seeing cloudy water. Readings below 80 are harsher on your pool — not only will chlorine treatments be less effective, you can even end up with long-term effects like surface degradation and metal corrosion. A whole lot of yikes.
The good news is that it’s easy to check for total alkalinity. Let’s get into it.
How to Check Total Alkalinity in Your Pool
You should check for total alkalinity at the same time you’re checking pH. Like our guy doublewide6 Repairs LLC says, you should invest in a solid kit and take your own readings to have the most accurate picture of what’s going on in your pool.
Skip to 3:30 to see him test alkalinity with a Taylor K-2006 test kit.
How often should you check total alkalinity?
If you’re checking pH twice per week, go ahead and test for total alkalinity at the same time. Don’t forget that pH ebbs and flows for a number of reasons, so you may have wildly different readings even within the span of a few days.
How is total alkalinity different from pH?
Total alkalinity and pH are closely related, almost cousins. A pH reading of your pool measures the acidity or alkalinity of the water on a scale of 0 to 14. Remember that 0 is the most acidic, and you’re shooting for 7.2 and 7.4 as your sweet spot.
Total alkalinity, on the other hand, measures exactly how many parts per million in your water have a certain characteristic (in this case, the presence of alkaline substances).
What is the ideal total alkalinity of a pool?
80 to 120 parts per million (ppm) is what you want to shoot for. There are some adjustments to make for pools with painted, vinyl or fiberglass linings — in that case, 125 to 170 ppm are more appropriate numbers. After you’ve run your test and made adjustments, you’ll want to give your water several hours to settle before you re-test.
Now let’s dive into the specifics of high and low readings.
What causes high alkalinity in a pool?
High alkalinity can occur for a few reasons, but one of the most common is by overcorrecting low pH. It’s possible to add too much sodium carbonate (better known as soda ash) or sodium bicarbonate (baking soda) while trying to increase pH and raise alkalinity.
Humans — and all the things they have on their body — are another culprit. Body washes, lotions, perfumes, and sunscreen can all throw off your pool’s pH level (a good reason to rinse off before taking a dip). Even a simple streak of sunshine can throw off your levels; rising water temperature is a surefire way to raise the water’s pH.
What causes low alkaline levels in a pool?
Low alkalinity means high acidity, which is bad news for your pool and its surfaces. After a heavy rain or backwashing with fresh water, the added water with unknown alkaline levels is likely to make an impact. The next course of action is to correct the imbalance by adding sodium bicarb or sodium carbonate.
The Stuff You Need
We don’t do affiliate links, FYI. Anything we’re recommending is something we’d use to monitor our pools, too. If we start doing affiliate marketing, trust us, we’ll mention it first.
Cheap test kit that checks for total alkalinity and pH:
Taylor K-1003 Safety Plus Swimming Pool Chlorine Bromine pH Alkalinity Test Kit | $19.48
More expensive, and more comprehensive test kit: