Household bleach is considerably cheaper than the granulated chlorine used for hot tubs, and we all know that bleach is a powerful disinfectant. So is it suitable for sanitizing hot tubs?
Liquid bleach should never be used in hot tubs because it lacks the concentration needed to properly disinfect the water. Household bleach has no stabilizing agents to protect from UV rays, which causes it to lose most of its effectiveness in just a few hours. The unsuitable pH levels in bleach also cause dry skin.
Although bleach is useless for sanitizing spa water, it can be used to clean and disinfect an empty hot tub using the correct technique, which I’m going to show you later on.
What happens if you use bleach in a hot tub?
The active ingredient in household bleach is sodium hypochlorite. Because of the similarity in its name to the active ingredient found in liquid chlorine (calcium hypochlorite), which is used to sanitize swimming pools, many wonder whether it’s suitable for disinfecting hot tubs.
The problem is that liquid bleaches such as Clorox are only 5% active chlorine. The active ingredient in specially formulated chlorine granules meant for hot tubs has a concentration of 55%, a whopping 11 times more.
It’s only at concentrations this high can it prevent algae and other nasty bacteria from growing in your spa.
The vast amount of water that a hot tub holds would dilute household bleach so much that it would no longer be able to disinfect. But don’t go thinking that you can just add more.
Household bleaches have a pH level that is way too high for use in hot tubs. By adding lots of bleach, you would need to use a whole load of other correcting chemicals to balance the water. What’s more, vast quantities of bleach would leave you with very dry and itchy skin.
Another issue with regular grocery store bleaches is that they aren’t stabilized. Clorox and other household bleach brands quickly burn out under sunlight, rendering any disinfecting qualities useless.
Regular bleach also only works properly when diluted in cold water. Since hot tubs are usually heated to somewhere between 95 – 104°F (35 – 40°C), bleach would have very little disinfectant power left.
Granulated hot tub chlorine is formulated from sodium dichloro-s-triazinetrione, better known as sodium dichlor.
Unlike household bleach, it has an almost neutral pH of 6.5, which means you don’t need to alter the pH levels every time you dose.
Sodium dichlor is also buffered with cyanuric acid (CYA). The buffer helps to keep the sun’s ultraviolet light from breaking down the chlorine when the spa is uncovered.
Unlike liquid bleach, dichlor stands up to the high temperatures found in hot tubs. Yes, it’s more expensive, but granulated chlorine has been specially formulated to sanitize spa water without damaging the hot tub.
Can you use liquid chlorine in a hot tub?
Liquid chlorine used in swimming pools has calcium hypochlorite as its active ingredient. So if it’s suitable for swimming pools, surely it’s fine to use it to sanitize a hot tub?
Liquid chlorine should never be used in a hot tub. Although the high heat in a hot tub rapidly dissolves and disperses the liquid chlorine, it doesn’t do so uniformly. The stabilizing agents in liquid chlorine aren’t suitable for hot tubs. The chemicals significantly alter the pH, making it very difficult to balance the water chemistry.
There is a vast difference between hot tubs and swimming pools: the size. An average-sized hot tub contains around 300 gallons, whereas a backyard pool holds some 15,000 gallons.
Because swimming pools hold such a large volume of water, adding concentrated liquid chlorine made from calcium hypochlorite (cal-hypo) doesn’t have the same immediate effects that it has on a hot tub.
Using pool chlorine can have disastrous consequences for your hot tub and will likely invalidate its warranty.
Cal-hypo has a high concentration of calcium and a high pH, which can leave deposits on parts of the heater and plumbing fittings.
Rubber seals around the jets, pumps, lights, and other O-ring components can harden and begin to disintegrate if pool chlorine is used in your hot tub.
Liquid chlorine can easily damage the acrylic or vinyl shell of your hot tub. Cal-hypo will strip the protective coating or membrane layer, leaving a white ring around the shell at the waterline.
Lastly, cal-hypo can irritate your skin, eyes, and nasal passages. In extreme cases, liquid chlorine can cause rashes and burns on the skin that may require medical treatment.
Can you use bleach to clean an empty hot tub?
While we’ve seen that adding household bleach to your spa water has almost no sanitizing effects, can it be used to clean and disinfect an empty hot tub?
Cleaning a spa with diluted bleach is an effective way of sanitizing and will not hurt your hot tub if used correctly. When bleach is added to water, it forms chemicals such as hypochlorite anion and hypochlorous acid that work to disrupt and kill bacteria.
Like vinegar, bleach is an excellent way of cleaning a hot tub when empty. Bleach is particularly useful for cleaning tough stains and scum lines that vinegar isn’t capable of getting rid of.
Bleach is also able of ridding your hot tub of nasty bacteria such as Pseudomonas aeruginosa, the cause of hot tub folliculitis.
When using household bleach to clean your hot tub, you first need to thoroughly rinse the spa.
Bleach must never be mixed with anything besides water, which is why it’s so important to rinse off any chemical residue left behind after draining the water.
Once you’ve rinsed the spa, combine equal measures of bleach and water in a bucket or spray bottle.
Apply the water-bleach mixture and allow it to work for 15 minutes. If you’re using a bucket and cloth, make sure to avoid creating huge puddles in the seating and footwell areas.
After a quarter of an hour, give the hot tub a good scrub with a sponge or soft rag. Rinse the spa thoroughly again to ensure no bleach is left behind.
Using a wet/dry vac in the seating and footwell area is the most efficient way to ensure you get rid of all the bleach. It’s also a lot less exhausting than trying to do it by hand.
While using bleach to clean and disinfect an empty hot tub won’t cause any harm, it’s important to understand the risks of using it to clean the spa filters.
Can you use bleach to clean a hot tub filter?
While it’s possible to clean hot tub filters with bleach, it’s not recommended because it causes damage to the fibers. Worn and damaged fibers result in the filtration being less effective. The damage also results in having to replace the filters prematurely.
There’s no doubt that cleaning spa filters in bleach will certainly destroy bacteria and other contaminants, leaving them clean and sterilized.
But the problem is that bleach is just too harsh and should only be used if you don’t have any filter cleaner available.
A dedicated filter cleaner has all the sanitizing ingredients you need but is much more gentle on the filtration fibers, meaning that you won’t have to replace them nearly as often.