The 3 Pillars of Clean Spa Water

While it’s not exactly rocket science, there’s something of a three-part equation for maintaining good water quality in a hot tub: circulation + filtration + water chemistry. 

Circulation moves the water, filtration removes particles and properly balanced chemistry keeps the water safe, clear and comfortable. “You can’t just choose one of these — all three are needed to maintain a clean and usable spa,” says Paul Gillio, product specialist with Solenis Pool Solutions.

When customers understand how the three elements work together, they’re better equipped to maintain clean water, protect their investment and avoid the most common maintenance mistakes.

Clean and safe

Water care starts with proper sanitization. When Alicia Stephens, director of training and education for BioLab, teaches a class to hot tub retailers, she stresses two must-haves: sanitizer and shock. “Always make sure there’s sanitizer in the water,” she says. “It’s doing so much of the work by breaking down contaminants. That’s the No. 1 thing.” 

Second, shock the water regularly. “People often forget to do that, especially first-time spa owners,” Stephens says. “They don’t realize sanitizing and shocking are two different things.” Shocking is the extra step to break down the contaminants like oil and lotion that naturally come off people when they soak in a hot tub; otherwise, the water gets cloudy or foamy and it’s difficult to keep clear. The sanitizer should go into the hot tub as soon as it’s being filled and should always be in the water.

Spa owners don’t have to be chemists, Gillio says, but they should routinely monitor sanitizer and pH. Sanitizer helps control germs, while pH affects sanitizer performance, bather comfort and the protection of spa functions and equipment. Test both twice a week using a quick and simple test strip. Common primary sanitizer systems include chlorine, bromine and PHMB/biguanide. “Spa owners must follow the product directions to determine the proper sanitizer levels and how much product is needed to make the adjustment,” he says.

Customers should always be aware of pH levels, which are specified by the spa manufacturer and sanitizer label. An ideal range is 7.2-7.8, and it can be adjusted with a spa-approved pH increaser or decreaser.

Total alkalinity and calcium hardness are also important because they help stabilize pH and protect spa surfaces and equipment. However, they don’t fluctuate that often. Balance them during the start-up and then test monthly or when pH becomes difficult to control (low alkalinity) or the spa has excessive foaming (low calcium).

Gillio recommends keeping the explanation of water chemistry factors simple for customers: “Sanitizer helps control germs, and pH helps the sanitizer work while protecting comfort and equipment. Total alkalinity acts as a buffer that helps keep pH stable, while calcium hardness helps protect surfaces and equipment from corrosive or scale-forming water.” Teach customers to check pH and sanitizer regularly and contact the retailer to check alkalinity and calcium hardness at start-up, after refilling and when issues arise.

The ‘three-legged stool’ of clean water

Stephens describes circulation, filtration and water chemistry as a “three-legged stool” to ensure the cleanest possible water in a hot tub. She compares circulation — or the pump — to the heart in a human body. “Your heart pulls oxygen through your lungs and pushes it out to keep you alive,” Stephens says. “The pump acts in a similar way — it pulls in water that needs to be treated, then pushes it back out where it gets filtered through a chlorinator. It’s like your heartbeat — it’s responsible for moving the water back out, so it’s safe for use,” she says. If circulation in a hot tub stops, it’s no longer able to “feed” water into the pump and it gets cloudy.

The filter, the all-important device that actually removes contaminants from the water, requires regular care and maintenance. Rinsing the filter occasionally doesn’t fully remove the debris from the mechanism. Chemical manufacturers recommend giving the filter a deeper clean every few months. Fill a bucket with warm water, add filter cleaner (not soap) to loosen the accumulated baked-in debris and let it soak, then air dry before reinstalling. “A good rule of thumb is to have two sets of filters,” Stephens says. “Take one out, clean it and put the dry one in.”

Common mistakes

Retailers can help hot tub owners extend the life of their spa by preventing a few common mistakes. Gillio often finds new owners test too infrequently, allow sanitizer to fall below the recommended range, neglect filter cleaning and underestimate the effect of heavy use. “New owners may use the spa often, quickly adding perspiration, body oils and other contaminants,” he says. Another common mistake is failing to use an oxidizer or shock treatment consistently for their particular sanitizer. A regular testing, filtration and maintenance routine helps prevent cloudy water and odors.

Stephens has found new owners minimize the amount of chemicals they put in the water. “People will say, ‘I’m going to soak in this water. I don’t want to put many chemicals in.’ Or they think the chemicals are bad, so they don’t put enough in, and they end up with foamy, cloudy water,” she says. “Chemicals are there for a reason. They’re not bad. They work well.”

Retailers should educate customers on how to follow a simple but effective routine that focuses on circulation, filtration and water chemistry to ensure safe, clean water for the life of the hot tub.