Hot Tub Water Chemistry and Maintenance

Some questions you might have:

1. What is the primary function of hot tub filters, and why is their maintenance crucial?
2. Describe the recommended cleaning frequency for hot tub filters, specifying the methods for weekly and monthly cleaning.
3. Explain the importance of pH balance in hot tub water, mentioning the ideal pH range and the potential consequences of imbalance.
4. What are the primary sanitiser options for hot tub water, and what are the recommended residual levels for each?
5. Outline the key steps involved in the quarterly draining and refilling of a hot tub.
6. List five common contaminants that contribute to cloudy hot tub water.
7. Describe the process of “shock dosing” a hot tub, explaining its purpose and the different types of shock treatments available.
8. Besides shocking, what other measures can be taken to clear cloudy hot tub water?
9. What are the primary causes of foam in hot tub water, and how can it be prevented?
10. Explain the purpose of shocking a hot tub in relation to sanitiser effectiveness and the removal of chloramines or bromamines.

The answers to your questions

1. Hot tub filters trap and retain solid and particulate matter, preventing water contamination. Regular maintenance ensures their effectiveness in maintaining water clarity, prolonging the hot tub’s lifespan, and optimising chemical efficiency.
2. Hot tub filters should be cleaned weekly by hosing them down with a strong jet of water to remove debris. Monthly cleaning involves soaking the filters in a specialist cleaning solution to remove ingrained contaminants.
3. Maintaining a pH balance between 7.0 and 7.6 is essential for bather comfort and the effectiveness of sanitisers. Imbalance can lead to skin irritation, equipment damage, scale formation, and reduced sanitiser efficacy.
4. The primary sanitisers are chlorine and bromine. Recommended residual levels for bromine are 2-4 mg/l, for inorganic chlorine 2-4 mg/l, and for organic chlorine 3-5 mg/l.
5. Quarterly draining and refilling involve using a system flush to clean pipework, flushing with a hose, cleaning the shell, vacuuming pipework and jets, refilling with water through the filter area, and adding chlorine or bromine during filling.
6. Common contaminants include environmental debris (dust, dirt, leaves), organic matter (dead skin, body oils), man-made organic contamination (cosmetics, detergents), heavy bather usage, and low sanitiser levels.
7. “Shock dosing” involves adding a concentrated oxidiser to break down organic contaminants and restore sanitiser effectiveness. Options include non-chlorine shock, chlorine granules, bromine granules, and one-shot sachet treatments.
8. Other measures to clear cloudy water include checking and adjusting pH and sanitiser levels, cleaning or replacing filters, and using a clarifier to bind small particles for filter removal.
9. Foam is caused by a build-up of products and total dissolved solids (TDS) in the water, aggravated by jet action. Prevention involves showering before use, rinsing bathing suits without detergent, using quality chemicals, regular shock treatments, and keeping the cover open for aeration.
10. Shocking revitalizes the sanitiser by removing chloramines or bromamines, which are byproducts of sanitiser action that reduce its effectiveness and can give false readings on test strips. This ensures the sanitiser can effectively kill bacteria and maintain water safety.

Useful terms

Sanitiser A chemical substance, such as chlorine or bromine, that kills or inactivates harmful microorganisms like bacteria and viruses in hot tub water.

pH A measure of the acidity or alkalinity of water, ranging from 0 to 14, with 7 being neutral. Ideal hot tub pH is between 7.0 and 7.6.

Total Alkalinity A measure of the water’s ability to resist changes in pH, acting as a buffer. Adequate alkalinity helps maintain stable pH levels.

Shock Dosing The process of adding a concentrated oxidiser to hot tub water to break down organic contaminants and restore sanitiser effectiveness.

Chloramines Chemical compounds formed when chlorine combines with ammonia or nitrogen-containing compounds in water. They reduce chlorine’s effectiveness and can cause irritation.

Bromamines Similar to chloramines, bromamines are formed when bromine reacts with ammonia or nitrogenous compounds. They also reduce bromine’s effectiveness and can cause irritation.

Clarifier A chemical additive that binds small particles in water, making them larger and easier for the filter to remove, enhancing water clarity.

Filter A physical barrier, typically made of pleated fabric, that removes solid debris and particulate matter from hot tub water, maintaining water clarity and hygiene.

TDS Total Dissolved Solids, a measure of the total amount of dissolved substances in water, including minerals, salts, and organic matter. High TDS can contribute to water problems like foam and cloudiness.

Bathing Load The ratio of bathers to the volume of water in a hot tub, influencing the rate of contaminant introduction and the need for water treatment.

Biofilm A slimy layer of microorganisms that can form on surfaces in the hot tub, potentially harbouring bacteria and affecting water quality.

Ozonator A device that generates ozone, a powerful oxidiser, to help sanitise hot tub water and reduce the reliance on chlorine or bromine.

UV System A system that uses ultraviolet light to kill or inactivate microorganisms in hot tub water, providing supplemental sanitation.

System Flush A chemical product designed to clean the internal plumbing of a hot tub, removing built-up debris and contaminants before draining and refilling.