Solving the Problem of Low Chlorine / Bromine Levels

by Tony Turbo.

How often have you tested your hot tub water only to find your chlorine or bromine level was too low or even 0 ppm? If you are brand new to spas, perhaps you’ve never had this experience but if you’ve had your hot tub for a while, you’ve seen this problem, likely fairly often.

The obvious reason for little to no sanitizer is you simply have forgotten to replace it. You might find your bromine floater is empty, your chlorine cartridge needs to be replaced, you haven’t added granular bromine in a week, or your salt system is set too low. Depending on your sanitation method, all are possible reasons for your low sanitizer level. Of course, the solution is just as obvious.

But what do you do when correcting these issues do not solve the problem? If you are thinking you’ve done everything right, why is your sanitizer level still low?


A fairly common problem is phosphates in your water. Phosphates will essentially combine with either chlorine or bromine so that the sanitizing form of both – what you are testing for – are no longer present in your water.

These are the same phosphates that are commonly found in fertilizer. I’ve seen more than a few folks walk across their lawn soon after fertilizing it, hopped in their spa, and found phosphates in their hot tub.

However, phosphates can come from many sources, including sweat, skin lotions, and (hate to say it) urine. Many folks question their washing machine detergent; however, this is a very unlikely source as most manufacturers stopped using phosphates decades ago and many switched to enzymes. From my own experience, locating the phosphate source is often difficult but the solution is pretty simple as many spa chemical companies market Phosphate Removers. They work by combining with dissolved phosphates to become a particulate (technically called flocculation) which your spa filters remove. You then clean your filters.

High Bather Load

All spa sanitation systems are adjustable for a reason.  The sanitation demand (we call it bather load) will change significantly depending on your use of your spa.  Sanitation demand includes dead skin cells, body oils, sweat, bacteria & other pathogens introduced to your spa, and mold & fungal spores in the air, etc.  Bather load increases as you have more of these in your water.  However, you would correctly guess that the largest impact on bather load comes down to 4 things.

  1. How many people are using your spa?
  2. How long are they using it?
  3. How clean were they before entering the spa?  A shower is always a good idea.
  4. How often are they using your spa?

The higher these are the greater the bather load, hence the need for an adjustable sanitation system.  If your system is set too low for the bather load, you will quickly have little to no remaining chlorine or bromine in your spa water.

Filtration Times Are Too Short

Bather load can also impact your spa filtration times, particularly if you are using “in-line” sanitation systems such as “The FROG®, @ease Smartchlor®, etc. or have a salt system installed on your spa. Both in-line systems and salt-systems rely on sufficient water flowing through their cartridges to introduce sufficient sanitizer to your spa. If your bather load is high, you likely also need to increase your spa filtration times, or increase your cartridge or salt-system settings.

Serum Total Maintenance To The Rescue

In addition to its other benefits, Serum Total Maintenance is a highly effective back-up, secondary sanitizer in your spa. You always want to maintain proper sanitation levels in your spa. Generally, these would be 3 – 5 ppm chlorine or 2 – 3 ppm bromine. However, Total Maintenance is doing two things in your spa water to ensure you always enjoy a great experience.

First, it is also killing all pathogens in your spa water and thereby reducing the bather load your primary sanitizer has to deal with. This means you likely can use less sanitizer or lower your salt-system setting. It also means that Total Maintenance is ensuring your spa water remains clear and safe for use even when your primary sanitizer level is too low.

Second, Total Maintenance is also a highly effective pH buffer. Chlorine killing efficacy is particularly sensitive to pH levels. The higher your pH the less effective chlorine becomes. So not only is Total Maintenance reducing the bather load in your spa, it is also ensuring your sanitizer, particularly chlorine, is effective at keeping your spa water free of dangerous bacteria, and other pathogens.

Thanks for reading,

Turbo Tony

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