If you are new to hot tubbing, you may have thought Alkalinity and pH were the same and not something to worry about. Other hot tubbers like yourself may not be sure about the difference. In this article will explore this pillar of water chemistry and how to correct it when things go wrong.
Let’s start with what Alkalinity is. Alkalinity is the presence of calcium, magnesium, and other compounds in your water that act as a buffer against swings in your pH level. It works to hold your pH levels in place, so it remains balanced, preventing rapid swings in your water chemistry. Think of it as your first line of defense for maintaining healthy, clear water.
When you test Alkalinity and the difference from what pH is. With Alkalinity, you are measuring your water’s capacity to prevent pH from drifting up or down. On the flip side, when testing your pH, you measure how acidic or basic your water is. So, to recap, Alkalinity comprises minerals that prevent pH from getting out of control.
Where should it be? The recommended alkalinity range for hot tub water is between 80 ppm and 120 ppm or parts per million. You can quickly test this at home using a reliable water testing kit or test strips. Beginners should test your water once a week. Once you get this down, skip a week and test your water twice a month if you use your hot tub regularly.
Our preference when testing water is what we call a drop kit. It uses reactive drops to measure your levels. I think the colors are much easier to read, and the color won’t change over time during the test as a strip does. If you prefer one-on-one advice, I recommend taking a cup-sized water sample to your local hot tub store, and they can check it for you.
You might be asking what happens if you ignore your alkalinity levels when your alkalinity dips below 80 ppm.
This can lead to a host of issues, including:
Going the other way, if your alkalinity climbs above 120 ppm.
This can result in:
What causes alkalinity fluctuations in your hot tub water? They can range from natural environmental influences like rain and other debris falling into your hot tub to bodily reactions of everyday products applied to your skin and hair. Even regular chemical treatments can have a plus or minus effect on alkalinity.
Let's dive in a little deeper into the causes of those highs and lows and how to fix them.
When you have high Alkalinity, the number one reason for this is using a water source that already has high alkalinity. Second is body oils and lotions introduced into the water while soaking in your hot tub. Another cause is going overboard with calcium-based chlorine that pushes your alkalinity upwards. The fourth one I learned while researching this article. As your water naturally evaporates, the minerals and other alkaline compounds in the water become more concentrated, leading to higher alkalinity levels.
Before discussing fixing your alkalinity, the first question you should ask yourself is how old the water is. If it is over four months old, it’s like expired milk. Dump it and start over!
When fixing high alkalinity, you have two options: one is Muriatic Acid, which is a liquid, and the other is Sodium Bisulfate, also known as pH down or decrease. It is available in both liquid and granular powder.
Your first choice would be the Sodium Bisulfate (pH down). Since a hot hot tub is a small body of water, this is a better option to adjust alkalinity. If your pH falls out of the 7.2 ppm to 7.8 ppm range. You can adjust it after you lock in your alkalinity.
The use of pH down is because, as you may have inferred, alkalinity and pH are tied together, so often, when you adjust one, you impact the other, and the next option is not as desirable.
Muriatic Acid, proceed with caution. This should only be used with extremely poor water conditions, as with some types of well water. While effective, it does require careful handling due to its caustic nature. Ensure to follow the instructions on the bottle or consult your local hot tub professional for proper use, even though it requires extra care. Instead, I recommend a trucked-in water source to fill your hot tub.
Now, what decreases your alkalinity? Like in low alkalinity, your water source or rain can be the issue. Also, using chemicals like chlorine or bromine in your hot tub can cause reactions that gradually lower alkalinity over time.
Even certain types of microbial activity in your water, while unpleasant to think about, can consume alkaline compounds as part of their diet. In addition to all of that, acidic oils and lotions can also alter your water chemistry and decrease alkalinity levels.
To raise your alkalinity, you would use ordinary baking soda, which is sodium bicarbonate. Lowering alkalinity will also have a small impact on pH levels since alkalinity and pH are interconnected.
When making any adjustments, I suggest doing them gradually. It’s better to do small doses rather than attempting a significant adjustment and overshooting the mark.
Keeping your alkalinity levels in check ensures a more enjoyable hot tub experience and adds to the longevity of your beloved hot tub and its components.