Understanding Hot Tub Chemical for Crystal Clear Water
Last week we took a close look at how to keep your water crystal clean and clear. This week, we'll look a little more in depth at each chemical your hot tub uses. Understanding what each chemical does and the appropriate recommended levels will help to make balancing the water much easier.
Total Alkalinity
Total alkalinity (referred to as TA) is the total level of alkaline substances dissolved in the water, such as carbonates, bicarbonates, and hydroxides. The alkalines act as a pH buffer which allows the water to be more resistant to pH level changes. The recommended TA is approximately 80-120ppm.
If the TA is too low, the pH level will fluctuate greatly between high and low and will be hard to get stable. Low TA can be corrected by adding an alkalinity increaser product to the water.
If the TA is too high, you will also have a problem with keeping your pH stable. You can add a pH decreaser to bring TA back into the correct range.
When TA is balanced, it normally stays relatively stable, however adding water can raise or lower the TA levels.
Calcium Hardness
Calcium hardness (or CH) is the total amount of calcium dissolved in the water. Calcium helps to control the corrosive properties of spa water, which is why soft water or using a water softener is not recommended when filling your spa. The low calcium content in soft water can cause the water to become corrosive to spa components and equipment, and may also cause staining on the hot tub shell. The recommended calcium hardness is 150-200ppm.
If the CH is too low, add a calcium hardness increaser.
If the CH is too high, add a stain and scale product to bring it back into proper range, or perform a drain and refill with fresh water.
pH Balance
The pH level is the balance between acidity and alkalinity. If the pH is too low, it can cause corrosion of metal fixtures and the heating element. If the pH is too high, it can cause scaling by allowing minerals and metals to form on surfaces and stain the hot tub shell. The ideal balance for pH is between 7.2 and 7.6.
Low pH is around 6.6-7.0 and needs to be adjusted higher by adding a pH increaser.
High pH is around 7.8-8.2 and can be corrected by adding a pH decreaser.
Sanitizers: Chlorine vs Bromine
Sanitizer is essential to kill bacteria, viruses, and organic materials in the spa. The two sanitizers approved for use in Canada are chlorine and bromine. Both work equally well when water chemical levels are checked and maintained regularly. Always test often and follow the directions on the bottle to know how much chlorine or bromine needs to be added to your spa.
Chlorine. If you decide to use chlorine as your sanitizer, granular chlorine is recommended. Chlorine tabs (also known as trichlor) are popular and can be convenient, but they are acidic and dissolve quickly in hot temperatures. Having spa water that is too acidic can damage your spa’s heater, jets, and pump internals, and even cause corrosion. Many spa companies will not cover damage caused by chlorine tabs, and using them can even void your warranty (always consult your hot tub's owner’s manual). Regardless of whether you use granular or tablet chlorine, check chlorine levels weekly using a test strip. If using granular chlorine, run the jets on high for at least 30 minutes with the hot tub cover open after adding it. Keep in mind that chlorine dissipates faster in higher temperatures.
Bromine. Bromine is another excellent sanitizer and has a lower burn-out rate than chlorine. It is available in both granular and tablet forms. Many spa owners choose to use both—keeping a bromine floater in the spa to maintain consistent levels and using granular bromine as needed for an extra boost.
Shocking Your Spa Water
While sanitizer kills bacteria, it leaves dead particles in the water. Shocking the water removes bacteria, burned-out chemicals, and other organic material from your spa. Avoid using a chlorinating shock, as its high acidity can damage your spa jets and internal components. An oxidizing non-chlorine shock is easier on equipment and can be used in both bromine and chlorine systems. A good shock schedule is once a week, after a heavy bather load, or if the water has a strong odor. When shocking, ensure that the jets run on high for 30 minutes with the cover open.
Additional Considerations for Water Clarity
Bather Load
The number of people using the spa, the length of time in the water, and the frequency of use all affect water quality. The average bather load is typically two people using the spa for 30 minutes about 2-3 times a week. If you use your spa more or less than this, adjust chemical levels accordingly. Always test your water frequently to maintain proper balance.
Filters
Clean and well-maintained filters are essential for keeping spa water clear. Filters remove particles and debris from the water, but they need regular cleaning to remain effective. Rinse your filter once a week with fresh water, soak it in a chemical solution once a month, and replace it with a new one once a year for optimal performance.
Keeping your hot tub water clean doesn't need to be difficult. Maintaining balanced chemicals and following a routine water maintenance plan will help ensure your water remains crystal clear. For more information on keeping your water clear, check out our previous articles on general water maintenance routines and how to keep your filters clean.
