How Do You Know When It’s Time to Change the Water in a Hot Tub?

Fresh, balanced water makes every soak more comfortable—and it helps your sanitizer do its job. But even a well-maintained spa eventually reaches the point where chemicals alone cannot restore the water. Here’s how to recognize when it’s time for a clean refill.

5 signs it’s time to change your hot tub water

Don’t wait for a calendar reminder if your water is already telling you something is wrong. A drain and refill is often the cleanest reset when you notice any of these signs.

1. The water stays cloudy after you balance it

Cloudiness can come from fine debris, body oils, minerals, or sanitizer that is no longer keeping up. Test and clean the filter first. If the water still does not clear after proper maintenance, drain and refill the spa.

2. Foam keeps coming back

A little foam can happen after use, but persistent foam commonly points to a buildup of lotions, soaps, detergents, and dissolved solids. If it returns shortly after treatment, fresh water is usually the better solution.

3. The water has an unusual odor

Clean hot tub water should not smell harsh or unpleasant. A strong chemical smell can mean the sanitizer is reacting with contaminants instead of working efficiently. Follow your product labels and, if the odor continues, drain and refill.

4. Your water chemistry is hard to keep balanced

When pH, alkalinity, or sanitizer levels swing repeatedly despite careful testing, the water may be overloaded. Changing the water gives you a much easier starting point.

5. The water feels gritty or you see scale

Gritty water, a rough shell surface, or visible scale are signs that minerals are building up. Address the water balance and filter condition, then refresh the water when buildup is persistent.

How often should you drain and refill a hot tub?

Use three to four months as a practical baseline, then adjust for how your spa is used. A hot tub used every day by several people will usually need a refill sooner than one used occasionally by one or two people.

• Heavy use: check the water closely and expect more frequent changes.
• More bathers: more lotions, body oils, and other contaminants enter the water.
• Hot weather and windblown dust: can make routine testing and filtration especially important in the Arizona East Valley.
• Water problems: cloudy, foamy, smelly, or stubbornly unbalanced water is a reason to change it early.

Your hot tub manufacturer’s owner manual and your sanitizer product label should always guide your specific routine.

Why old water becomes difficult to manage

Every soak adds small amounts of sweat, body oils, lotions, cosmetics, and other dissolved material to the water. Over time, those total dissolved solids can make water look dull, feel less pleasant, and demand more from your sanitizer and filtration system.

In areas with mineral-heavy fill water, scale can add another challenge. Regular filter cleaning, consistent testing, and timely water changes help protect the spa surface and keep your care routine simpler.

A simple drain-and-refill routine

For a more thorough reset, clean the plumbing as well as the shell. Marquis recommends purging plumbing before draining when appropriate, then cleaning filters and the acrylic shell before refilling. Always follow your specific owner manual and product labels.

1. Review your owner manual. Follow the manufacturer’s instructions for powering down, draining, and restarting your specific model.
2. Clean the filter. Rinse or clean it as directed; replace it if it is worn or damaged.
3. Drain the spa responsibly. Follow local requirements and avoid directing water where it could cause damage.
4. Wipe the shell. Use a hot-tub-safe cleaner and avoid household products that can leave behind residue.
5. Refill and balance. Once the spa is full, test the water and adjust your sanitizer and balance levels according to the product instructions.
6. Run the circulation system. Give the water time to circulate before using the hot tub.

Arizona’s hard-water factor

Arizona heat, wind, and mineral-heavy fill water can make a calendar-only schedule less reliable. As water evaporates, dissolved minerals stay behind; topping off adds more minerals. That is why hard-water owners should watch water clarity, scale, and total hardness—not just the date of the last refill.

For Marquis hot tubs, total hardness is generally targeted at 150–250 ppm. If your source water is especially hard, a five-stage hose pre-filter can reduce minerals before they enter the spa. Keep the cover on between uses, clean the filter on schedule, and move up a water change if scale, grit, or stubborn cloudiness returns.

After a dust storm or unusually heavy use, rinse the filter, test the water, and restore sanitizer as directed by your products. If the water still will not rebalance, a fresh fill is usually the better reset.