How often should you test hot tub water?

Hot water changes faster than pool water. A few soaks can use up the sanitizer and move the pH, and you cannot see either by looking. A quick test is how you find out before the water turns.

Test again when

• The tub has had a busy day, a party, or guests.
• Nobody has used it for several days and you are about to.
• You have just refilled it, or added a lot of fresh water.
• The water looks or smells different from usual.

Getting a reading you can trust

• Take the sample away from the jets, with the pumps off, and dip to about elbow depth.
• Read each pad at the time the bottle says. A pad read too late shows the wrong color.
• Keep fingers off the pads and the cap on tight. Damp strips go bad.
• Check the date on the bottle. Old strips read wrong.

Writing readings down is what makes them useful: one low reading is a blip, three in a row is a pattern. See what the readings mean.

This is general guidance. Your hot tub's owner's manual comes first, and so do the instructions on your products.

Sources: Clorox Pool&Spa: How to maintain your spa or hot tub.