How do you test hot tub water?
Owners test chlorine and pH, and the CDC says to follow the maker's directions for the test you use. In the One Model, you test with a strip once a week and enter the result in the app, while Waterlab reads pH, ORP and temperature in the plumbing.
What do you test for in hot tub water?
Two things come up in every source: chlorine and pH. The CDC says it is the owner's responsibility to check both regularly, and that owners must routinely test and adjust them.
The CDC recommends at least 3 ppm of chlorine in a hot tub and a pH of 7.0 to 7.8. The King County public health hot tub guide (Seattle and King County, Washington) says a good kit also measures total alkalinity, and that an owner needs a test kit to keep a hot tub in balance.
Are test strips accurate?
Strips are easy, and they are less accurate than a DPD test kit. That is the CDC's wording. It adds that no matter what test you use, you should follow the manufacturer's directions.
The King County guide goes further. It calls the DPD kind the better one to have, because it measures free chlorine, which is the chlorine available to kill germs. It recommends a kit that reads free chlorine, combined chlorine, pH and total alkalinity. It warns that some kits sold to the public do not give accurate readings at hot tub temperature.
So a strip is a quick check, and a DPD kit is a closer one. If a result looks odd, a second reading is sensible. Good Hot Tubs has not said whether it recommends a DPD kit alongside the weekly strip.
What is free chlorine, and why does it matter?
Free chlorine is the chlorine still in the water that is ready to kill germs. The King County guide says some chlorine gets used up or combined with other substances in the water. The part that is left is the free chlorine residual, and it is the number you want to see.
Total chlorine is a different figure. The guide says it is free chlorine plus combined chlorine, and it is not the amount available for disinfecting. That is the reason the guide prefers a kit that reads free chlorine.
How do you test hot tub water with a strip?
Follow the directions on the pack. They are the maker's directions, and the CDC says to use them. Read the result the way the pack says.
The King County guide says to test often enough to keep the water balanced. How many people use the tub, and the weather for an outdoor tub, both change the balance. It says to check the chlorine level regularly, and especially just before use.
How does the One Model handle water testing?
Once a week, you test the water with a strip, enter the result in the app and check the salt system's run time. That is the weekly routine.
Beside the strip, Waterlab does its own job. It sits in the plumbing and reads pH, ORP and temperature. ORP is a measure of how well the sanitiser is working. The app (Gecko in.touch 3) shows the readings on your phone, so you can check the water before you lift the cover.
The salt system makes the chlorine, and the app tells you what the water needs. Good Hot Tubs describes the aim as far fewer chemicals to buy and handle.
When should you test outside the weekly routine?
Test when the water looks or smells wrong. The King County guide says a foul smell or heavy chlorine odour, or burning eyes, is a reason to test for free chlorine. It says cloudy, coloured or foamy water is a reason to check pH and chlorine.
Test after heavy use too. The guide says chlorine is used up faster in a hot tub than in a swimming pool, and that a long soak with several people uses more. In the One Model, the app and Waterlab readings are the quick look, and a strip adds a hands-on result.
What do you do with a test result?
The CDC says to adjust as well as test. If chlorine or pH is outside the range, you correct it. Products exist to raise pH and products exist to lower it, and a pool supply store can advise on them.
In the One Model, you enter the strip result in the app, and the app tells you what the water needs. If a result worries you, contact Good Hot Tubs. Once a year, you book a check-up with your local expert.
Questions
How often should you test hot tub water?
For the One Model, once a week with a strip, entered in the app. For any other tub, follow the maker's directions.
What is a DPD test kit?
The King County guide describes it as a kit that reads free chlorine, combined chlorine, pH and total alkalinity. The CDC says strips are less accurate than a DPD kit.
Does the app test the water for me?
Waterlab reads pH, ORP and temperature in the plumbing and the app shows them on your phone. The weekly strip is still your part of the routine.
Can a lab test hot tub water?
The King County guide says total dissolved solids can be tested through a pool maintenance service or a private laboratory.
Sources
General facts on this page come from these public sources. Facts about the One Model come from Good Hot Tubs.
- Home Pool and Hot Tub Water Treatment and Testing. U.S. Centers for Disease Control and Prevention (CDC).
- Staying Happy and Healthy in Your Hot Tub, sixth edition (PDF). Public Health, Seattle and King County.
Related answers
Is the One Model right for you?
Ten questions about your home and how you would use a hot tub. You see your result before you give any contact details, and you can ask for a test soak on Vancouver Island when you send it.