PH and Alkalinity and Why They Matter

PH and Alkalinity and Why They Matter

Most hot tub and pool owners are aware that they need to maintain a proper pH and alkalinity in their water, but few people actually know why. In this post I will go over what pH and alkalinity are and why they matter.

What is pH?

The pH scale

pH stands for "potential of hydrogen" and is the measure of how many hydrogen (H+) ions are present in water. The less hydrogen ions there are in the water the more acidic the water becomes. pH is measured using the pH scale you're familiar with from science class where 7 is  neutral, 0 is the most acidic, and 14 is the most basic (also known, confusingly, as alkaline). This scale is logarithmic and not linear; meaning that as you go from one number to the next you increase or decrease acidity by a factor of 10 and not one. (For example, water with a pH of 6.0 is 10 times more acidic than water with a pH of 7.0).

What is alkalinity?

Total alkalinity of water is a measurement of how much acid the water can neutralize without changing the pH. As things are added to the water that could raise or lower it's pH, alkalinity will act as a buffer and prevent sudden shifts in pH. It is measured in ppm (parts per million). The higher the ppm, the more buffering ability the water has, and the less the pH will be affected by highly acidic or basic substances being added to the water.

What causes changes in pH and alkalinity?

The short answer is basically everything and everyone that goes in to the water. Everything has its own pH and alkalinity. If you add something to the water (Including humans. Our skin is fairly acidic with a pH of around 5.5) that is acidic/basic or has low/high alkalinity you will lower/raise the overall pH or alkalinity of the water.

pH in Hot Tubs and Pools

So how does this relate to pools and hot tubs? There are four main things that pH will affect; bather comfort, water clarity, chlorine efficiency, and the longevity of the equipment. Equipment in this case refers to pumps, heaters, filters, o-rings and gaskets, pool liners, concrete pool finishes, hot tub jets, pillows, covers and basically everything else that comes in contact with the water.

Cloudy water caused by high pH.

Water with a pH of less than 7 will start to become more uncomfortable and will wear out equipment quicker (especially anything made of metal). Water with a pH of more than 7.8 will also become uncomfortable, can become cloudy looking, cause scaling on surfaces of pools and hot tubs, and reduce chlorine's effectiveness.

The pH of your eyes is slightly basic, sitting around 7.3-7.5. By keeping the pH in the ideal range of 7.4-7.6 you will greatly reduce the red, irritated feeling eyes that many people experience when swimming in unbalanced pools while also keeping your chlorine working effectively, keeping your water clear and getting a longer life from your equipment.

Alkalinity in Hot Tubs and Pools

A hot tub heater element that has been
corroded by low pH.

The ideal range for total alkalinity is between 80-120ppm in hot tubs and between 80-150ppm in pools, depending on the finish of the pool. Water with an alkalinity less than 80ppm won't be able to buffer acids well; leading to rapid fluctuations in pH (tending to stay on the acidic side). Water with an alkalinity higher than 150ppm is buffering too well. The pH of the water will stay the same or raise despite pH reducers being added to the water. This can lead to the discomfort, cloudy water, chlorine inefficiency, and scaling that high pH brings.

Tips and Best Practices

Always adjust alkalinity before pH. Wait between 2-3hrs for a pool and 1hr for a hot tub after adjusting alkalinity before adding any other chemicals. This will give the alkalinity booster/reducer a chance to fully work and give you the most buffering ability before adding anything else.

• Adding air to water will increase it's pH. Turn your hot tub's air controls off when you get out to prevent pH creeping up on you.
• Make sure to regularly change the water in your hot tub (between 2-4 times a year, depending on usage) to keep the chemicals you add working at peak efficiency.
• Make sure to get your water professionally tested at least once a month as the test kits at a pool or hot tub store are generally far more accurate than home test kits/test strips.
• If your test kit is always reading low the reagents/test strips may be expired. Bring a water sample to your local pool or hot tub store and see how the readings line up. If the water test results are higher than what you tested it's time to replace your reagents/test strips.
• Is your water looking crystal clear? It might still need balancing; just as basic water can become cloudy, acidic water can be very clear.

Anything we missed? Add your suggestions in the comments section below.

The Spa Shoppe is a hot tub and pool supply store in Whitby, Ontario. We carry the full line of Hydropool hot tubs and swim spas; and offer service on all brands of hot tubs, pools, and swim spas. Like us on Facebook (www.facebook.com/TheSpaShoppe) or follow us on Twitter (@thespashoppe) to get notified when new blog entries are posted.

How To Save On Your Hot Tub's Monthly Energy Cost

Welcome to The Spa Shoppe's first blog! This will be a blog aimed at teaching hot tub, and pool owners how to get the most out of their hot tubs, and pools. We will discuss everything from water chemistry (and why it's important), to proper maintenance (with the least amount of work), to troubleshooting problems (and how to prevent them from happening). I thought I'd start out by talking about something that everyone wants to know, how to save money on your hot tub's monthly hydro bill.

Fixing Leaks

Most hot tubs today are fairly well insulated when new; however foam hot tub insulation, and covers can become waterlogged and lose effectiveness over time. If you notice a leak be sure to get it fixed as soon as possible. You're losing water that you've already paid to heat and have to replace it with cold water that you have to then pay to heat. Once the leak has been fixed be sure to also remove and replace any insulation that has become saturated. Foam insulation works by heating the air bubbles within the insulation. If it gets wet and those air bubbles become water bubbles it loses most of it's insulating value.

Covers

Thermal image of the centre of a hot tub
cover without a full hinge sealer.

For that same reason you should replace your hot tub covers as they become saturated. When buying a new hot tub cover check to make sure it has a "full foam" or "full hinge" seal. This is a piece of foam that runs the entire width of the cover and is designed to insulate the center of the cover when the cover is closed. Without this you will only have a thin piece of vinyl insulating the hot tub between the two foam sides of the cover. 

Programing Your Filtration

Check your owner's manual to see if your hot tub allows you to control it's filtration cycles. Most newer hot tubs will allow for at least some degree of controllability over the start time and run time of the hot tubs filtration. Program your hot tub to only run mid day, or overnight to avoid peak energy rates; most hot tubs will only need to run 8-12 hours a day to properly filter the water with average use. Some hot tubs now allow you to program each day to run differently to account for the different peak energy times on weekends. Note: Some hot tubs that use a circulation pump to filter the water are designed to run for 24hrs a day and shouldn't be changed. Check your owner's manual for more information.

Economy Mode

If you're going on vacation, or just won't be using your hot tub for a few days check to see if you can set to economy mode. This will drop the set temperature 10-20 degrees, and only heat the water on a filtration cycle. Some manufacturers even have preset programs that allow will automatically switch between economy mode during the week and standard mode during the weekend if you are a weekend only user. Note: Economy mode should only be used if you are not planning on using the hot tub for two or more days, any less than that and it is more efficient to keep it at a set temperature. You can instead lower the set temperature by 2 degrees. Even a 2 degree drop can make a big difference in the energy consumption of a hot tub.

Miscellaneous

• Clean or replace dirty filters. A dirty filter doesn't allow water to pass through it as easily as a clean filter does; making the pumps work harder to keep up.
• Shut your air controls off when you're not using the hot tub. The air that is added will cool down the water and cause your heater to work harder to keep up.
• Make sure to lock your cover clips when you're not using the hot tub. These clips help to keep the cover firmly closed; without them the cover can be lifted by the wind, or from positive air pressure building up under the cover if your air controls are left open. This will allow heat to escape. If your clips are broken you can buy replacement clips from your local hot tub store.
• You can install a floating thermal blanket that sits on the hot tub water; adding another layer of insulation and slowing evaporation. If you have a well insulated hot tub a significant amount of the overall heat loss will come through evaporation.

Anything we missed? Add your suggestions in the comments section below.

The Spa Shoppe is a hot tub and pool supply store in Whitby, Ontario. We carry the full line of Hydropool hot tubs and swim spas; and offer service on all brands of hot tubs, pools, and swim spas. Like us on Facebook (www.facebook.com/TheSpaShoppe) or follow us on Twitter (@thespashoppe) to get notified when new blog entries are posted.