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Can You Use Chlorine in a Hot Tub?

Recently, we were asked the question, "Can you use chlorine in a hot tub?" To which we replied in effect: it all depends on what you mean by 'chlorine.' This question often comes up when someone runs out of granular chlorine for their hot tub. They either find some swimming pool chlorine after rummaging through their shed, or purchase swimming pool chlorine with the thought of saving some money. Yes, when you look at the label found on liquid chlorine (sodium hypochlorate) the ingredients are confusingly similar to the granule chlorine made for hot tubs. But, using this type of chlorine isn't as easy as simply tweaking the concentrations and hoping for the best; swimming pool and hot tub chlorine are altogether entirely different products. The same is true with liquid bleach.

While swimming pool chlorine seems like it would be a budget-friendly alternative to expensive hot tub granular chlorine, going this route will cost you far more in the long run than you would expect to save by foregoing the granular chlorine designed for your spa.

What is the Difference Between Pool and Hot Tub Chlorine?

While it's safe to use in swimming pools, liquid chlorine should never be applied to hot tubs. Yes, the products are similar, but there are a number of important differences between hot tubs and swimming pools. For one, swimming pools have a much larger volume of water, so dumping concentrated liquid chlorine into a swimming pool doesn't have the same, immediate effect as in a hot tub. So, the volume of water is one major difference. But, there is also the issue of temperatures. The high heat in a hot tub rapidly dissolves and disperses liquid chlorine, but not uniformly. Liquid chlorine made for swimming pools also contains certain chemicals that are meant to stabilize the chlorine, which works well for pools, but not so much for hot tubs. These stabilizers will throw off your pH and make it increasingly difficult to balance your hot tub's water.

What do all these differences mean to you and what could go wrong if you do accidentally use liquid chlorine? Let's find out.

But, What Could Go Wrong?

Let’s pretend that you used liquid chlorine in your hot tub, then in hindsight realized this maybe wasn’t such a great idea. You then booted up your laptop or pulled out your smartphone to do a few Google searches. Some results are reassuring, but others make bold warnings against using liquid chlorine in your hot tub. So, what could go wrong with your hot tub if you don't heed the warnings, or are worried about the liquid chlorine you recently added to your hot tub?

Deteriorated rubber fittings — Rubber seals around the lights, jets, pumps, and other O-ring components within your hot tub can harden and begin to disintegrate if a liquid chlorine is used in your hot tub.

Fluctuating pH levels — Liquid chlorine (sodium hypochlorite) often comes with a number of stabilizing agents that work well in swimming pools but can wreak havoc on your hot tub's pH levels, often causing them to skyrocket and remain unwieldy. To make matters worse, this type of chlorine already has an elevated pH, which can cause maintenance issues while also causing calcium scale to form more rapidly.

Damage to shell — Liquid chlorine can easily damage the acrylic or vinyl shell of your hot tub. These types of shells often have a protective coating or membrane. Liquid chlorine readily reacts with this layer and also the chemicals in the shell.

Damage to shell's appearance — If you use liquid chlorine, you may notice a white ring around your shell at the waterline. This is caused by the liquid chlorine stripping away the protective layer. Your shell may also lose some of its luster due to the chemical breakdown.

Irritation for users — Liquid chlorine, when it comes into contact with people, can irritate the skin, eyes, and nasal passages. For those with dyed hair, liquid chlorine can cause discoloration, giving it a greenish hue. In extreme cases, bleach can cause rashes and burns on the skin that may require medical treatment.

It's not just liquid chlorine that is bad for your hot tub; other chemicals that are safe for swimming pools are bad for hot tubs, notably chemicals containing soda ash and Tri-Chlor.

How to Choose the Right Hot Tub Chemicals

There are many options out there to sanitize your tub's water without jeopardizing your health, budget, or the various components of your hot tub. Now if you are setting up your hot tub you have some options when it comes to sanitizers, but the two most popular are bromine and granular chlorine. (Master Spas hot tubs require you use chlorine with their eco pur filters.)

If you choose to go the bromine route, a simple, yet effective setup can include the Bromine Floater and the 1.5-pound tubs of SpaBoss Bromine Tabs. For those wanting to go the route of granular chlorine, we recommend the SpaBoss Chlor-Aid product. This product is simply the easiest way to get your tub’s water disinfected without altering its alkalinity or pH.

Have questions? Need some over-the-phone persuasion to help you put down that bottle of bleach or swimming pool chlorine? Drop us a line , we’d love to help!