Crystal clear, odorless, silky, fresh and clean. That is how properly-balanced hot tub water should look and feel. Maintaining the sanitizer level is an important part of the equation. But adding too much can cause issues.

For one thing, if your sanitizer level is too high it can bleach out the test strip making it read “no result.” This would prompt you to add even more sanitizer and further overdose your system.

On the other hand, what if your levels are fine, but your hot tub seems to be consuming too much sanitizer? Whatever the case, this article will help you identify the problem and correct it.

Too much sanitizer can damage hot tub components

Symptoms of Excessive Hot Tub Sanitizer

In most cases, excessive sanitizer will not permanently damage the operation of your hot tub, but it will accelerate wear and tear on certain components, which are replaceable. (Plus, damage obviously caused by overdosing can void the warranty.) Common examples include:

  • Cosmetic decals/appliques discoloring, bubbling or peeling (pictured left).
  • Foam headrests/pillows deteriorating or blistering, especially near the water line (pictured middle).
  • Rubber seals or gaskets inside of diverter valves wearing out prematurely.
  • Valve covers appearing dull or faded (pictured right).
  • Jet faces below the water line appearing dull or faded compared to jet faces above the water line.
  • Hot tub cover becoming discolored or “bleached” underneath in a short period of time.
  • Stainless steel parts rusting or pitting.

Beyond the hot tub itself, you might experience mild physical discomfort, such as eye or skin irritation, dry or brittle hair, or a strong chemical smell. Bathing suits may also wear out or fade prematurely. Would this mean you should stop using sanitizer altogether? Actually, sanitizer is required to maintain clean, safe water. But you are not without options.

Frog @ease Smartchlor sanitizer

Which Hot Tub Sanitizer is Best For You?

Several different sanitizers are approved for hot tub use. But you may prefer one over another, perhaps due to sensitive skin. Target levels are measured in parts-per-million (ppm) using the appropriate test strip:

  • Chlorine (dichlor) has been in use the longest, but is less preferable for people with sensitive skin. Using six-in-one test strips, the target level for “free chlorine” is between 3-5 ppm. Free chlorine above 5 ppm is too high.
  • Bromine is more stable in hot water than chlorine. It is available in granules, or automatic slow-dosing cartridges which are preferable for people with sensitive skin. (See ConstantClean+.) Using six-in-one test strips, the target level for bromine granules is between 4-6 ppm. Using Frog® Serene® test strips for bromine dual-cartridge (in-line or floating) systems, the target level is between 1-2 ppm. Bromine above 6 ppm is too high.
  • SmartChlor® (pictured above) is the latest sanitizer developed. Due to its unique molecular structure, it remains effective at lower concentrations than bromine or chlorine. In the United States, it is available in automatic slow-dosing cartridges which are preferable for people with sensitive skin. (See ConstantClean+.) Using Frog @ease® test strips, the target level for Smartchlor dual-cartridge (in-line or floating) systems is between 0.5 to 1 ppm. This translates to a light green color reading on the test strip.

What about salt? Saltwater systems generate sanitizer by converting sodium chloride into chlorine, or sodium bromide into bromine. Several major manufacturers promote the misconception these systems are “chemical-free” or “maintenance-free.” Go here to get the facts.

Happy Couple Marquis Hollywood Hot Tub

How to Avoid Excessive Hot Tub Sanitizer

Basically, your hot tub routine should include four steps:

  • Test your water weekly: Experienced owners test before soaking, and a few times per week when the hot tub is not in use. Make sure your test strips are compatible with your sanitizer.
  • After testing, balance the water as needed: This usually involves the total alkalinity and pH balance levels.
  • After balancing, add sanitizer (or adjust cartridges) as needed: Follow the sanitizer instructions, and allow sufficient time for chemicals to circulate before closing the cover.
  • Periodically, add non-chlorine shock oxidizer (or, “spa shock”): See below for more information.

Spa shock helps to refresh your hot tub water without disrupting its sanitizer level. Once per week is the average for bromine systems, and once every two weeks is typical for SmartChlor systems. (If your hot tub is equipped with an ozonator, adding spa shock supplements the work of the ozonator and further refreshes the water.) After adding spa shock, do not close the cover immediately. Run the jets for 30 minutes with the cover off, then close and secure the cover.

Remove the cover and run the jets to ventilate your hot tub.

How to Lower Hot Tub Sanitizer Level

If your sanitizer level is too high, follow these steps to reduce it:

  • Ventilate: Remove the spa cover and run the hot tub jets on high for 30 minutes. Then, test the sanitizer level again to confirm the reading is back to normal.
  • Dilute: If the sanitizer level is still too high, turn off the jets and drain your hot tub about halfway.* Then, add fresh water to dilute the remaining sanitizer. After refilling with fresh water, run the jets on high for 30 minutes and then test the water balance and sanitizer level again as noted on the test strip. (To avoid stressing sensitive plants, shrubs or lawn, route your drainage hose accordingly.)
Group hot tub soaking may consume more sanitizer.

Hot Tub Consuming Too Much Sanitizer?

What if your sanitizer level is within the recommended range, but it seems like your hot tub is using too much sanitizer? Here are some common reasons:

  • Your hot tub gets used several times per week.
  • Your hot tub is frequently used by multiple people.
  • Your guests do not typically rinse off before soaking.
  • Your hot tub cover gets removed for long periods of time (such as during parties or barbecues).**

Naturally, the more often a hot tub is used the more sanitizer it will consume. This is not a bad thing; it just means your sanitizer is doing its job. That said, two simple habits will help to reduce sanitizer consumption:

  • Rinse off in the shower before soaking. The less body oil, lotion, hair products and deodorant you bring into the water, the less sanitizer your hot tub will consume.
  • Keep the cover on whenever the hot tub is not in use.

Is there anything else you can do? If your hot tub is not equipped with an in-line sanitation system, you might consider using a dual-cartridge floating system (mentioned earlier) which may help to decrease sanitizer consumption.

Periodic draining, cleaning and refilling makes your hot tub water much easier to balance.

Benefits of Hot Tub Maintenance

Hot tub water is much easier to maintain when you periodically drain, clean and refill your hot tub with fresh water.* Based on your usage habits, this should be done a few times per year. Granted, it takes a few hours. But just like the family car, your hot tub will perform better, last longer, and look newer with consistent maintenance.

Need Help?

Your local Marquis® Dealer is a bona fide water care expert with a keen understanding of your local water supply. They can help you troubleshoot water quality issues, recommend Marquis-approved spa products, and supply you with replacement parts such as cosmetic decals/appliques, foam pillows, rubber seals and gaskets, and hot tub covers.


*For instructions on how to drain, clean, or refill of your Marquis hot tub, please refer to the owner’s manual. You may view or download a PDF version here. Otherwise, please contact your local authorized Marquis Dealer for assistance.

**Your hot tub cover does more than conserve heat and energy. It safeguards children and small pets, keeps debris out of the water, and protects the spa acrylic from UV damage and abrasion. In addition, since UV light breaks down chlorine and bromine, keeping the cover on when your spa is not in use helps to conserve sanitizer.