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Clean hot tub

Or: How to keep my hot tub perfectly clean.

Sometimes dealing with the chemicals that are required to keep your hot tub water clean and well maintained can be a bit confusing. Relax. You don't need an advanced degree in organic chemistry. Here's an "Intro to Hot Tub Chemicals", that will help clarify the things you need to do to continue enjoying your hot tub in a safe and healthy manner.


Sanitizing your hot tub water is the most important maintenance you can do for yourself. Why? Sanitizers kill the bacteria that can grow in warm water. Here's a quick summary on the different types of sanitizers:


(highly recommended) Highly effective and 'self-shocking,' ONEShock / dichlor is a balanced form of chlorine that can be used both as a sanitizing shock and residual sanitizer. When used correctly with the ecoONE® system, you will not experience chlorine smell, itching or rashes.
Do not use (white tablets, similar in appearance to bromine) Never use trichlor as a spa sanitizer. Generally used in swimming pools but it's highly corrosive in warm water. It may damage your spa, cause respiratory issues and WILL void most spa's warranty.

You're probably familiar with chlorine as the primary sanitizer used in pools. Chlorine can be used in a different concentration in hot tubs. There are chlorine tablets and chlorine granules created specifically for hot tub use.


Bromine can be added to a hot tub in the form of tablets, nuggets or granules. One form is sodium bromide, which needs to be activated with an oxidizer such as chlorine or Potassium Monopersulfate (non-Chlorine) shock. Another bromine product is BCDMH, which is a self-activating chlorine bromine combination. Many people choose bromine over chlorine because bromine is an effective sanitizer in hot tubs as it doesn't "gas off" at temperatures higher than 98 degrees and produces fewer odors than chlorine. Bromine works in a wide range of pH levels. Bromine is generally distributed through a floating feeder or cartridge system.


Biguanide (bi-gwan-eyed) sanitizers are non-chlorine, non-bromine products that kill bacteria by attacking the cell wall. The elimination of organics is accomplished with a hydrogen peroxide-based oxidizer used to "burn" off the organic matter and keep the water clear. This system produces fewer odors than chlorine or bromine and does not "gas off" at spa temperatures. Biguanides are generally not compatible with Enzyme systems.

Supplemental Purification Systems & Products

These systems are intended to assist, but not entirely replace, your sanitizers in keeping your hot tub clear of contamination.


Enzymes are not sanitizers. Enzymes are bio-catalyzers. Enzymes work in conjunction with sanitizers, ozone, mineral and ionic systems, boosting their action. Enzymes are used to minimize the use of harsh chemicals and to maximize their effect. The enzymes in a spa are positively charged to attract any oils, organic particles and by-products in your spa and hot tub. They then bond to these contaminants and dissolve them away allowing them to be effortlessly filtered from your spa and hot tub water. They also soften the water and keep minerals from building up along the water line effectively eliminating the spa & hot tub equivalent of "bathtub ring". Enzymes work very well in spas and hot tubs because the warm water helps to speed up the degradation process. The end products of the process are harmless, inert, and there are no residues to build up. To further improve the water quality, an Ozone Generator will make a big improvement and reduce chemical usage. It will provide oxidation and reduce chlorine usage, even more.


Ozone is an oxidizer and not a sanitizer, but it reduces the work of the sanitizers and lowers the level of sanitizers needed in the spa to keep it clean. The ozone process requires that your hot tub is equipped with a piece of equipment called an "ozonator." Even if you have an ozonator, you will need to supplement your water with a low level of sanitizer like bromine or chlorine. (Don't let anyone tell you otherwise. The idea that a hot tub can be thoroughly sanitized with ozone alone is a myth.) Ozone is compatible with bromine, chlorine, biguanide and mineral systems.


There are numerous ionizers, both Passive and Active, on the market today:

  • Passive ionizers are also called "Mineral Sanitizers" and they come in cartridges that are typically placed inside your filter or are contained in a floating dispenser through which the sanitizing minerals are slowly released into the water over time.
  • Active ionizers are sold as solar floaters, some are electric copper and silver ionizers and others are electric copper ionizers, and are installed as part of the circulation system.

Note: In general terms, ionizers do a good job of killing organic substances in the water but ionization alone is not sufficient to sanitize your spa water. Ionizers still require chlorine, bromine or other chemical oxidizers to be added to the water to provide adequate sanitation of the water.

Many people prefer to use mineral sanitizers because of the lower levels of chlorine or bromine.

Changing Your Water

Be sure to change your water about every 90 days, systems depending and on the amount of use of your hot tub (with EcoOne you change the water only once a year). Using Pipe Cleanser will remove chemical build up from chlorine or bromine products, as well as organic build. No amount of chemical additives can protect you completely in water that is old and dirty. You wouldn't wash your dishes in year-old water would you? Changing water is a simple task which you, your family and guests will be glad you did.

Cleaning Your Hot Tub

Cleaning the Filter

It's extremely important to keep your hot tub filter clean, so you should do it at least monthly. We recommend that you clean your filter with a good specialized hot tub filter cleaner a few times and replace it once a year. If you use EcoOne Filter Cleanser and clean it regularly you can extend the life of the filter up to a year longer.

Cleaning the Tub

To prevent the dreaded "Hot Tub Scum Ring" the first line of defense is regular water replacement and proper sanitation. A scum prevention product can also be used to help prevent the build-up of oils and greases on the water surface that combine to form the ring. If it's too late and you're already a scum victim, use a multi-purpose spa surface cleaner and a cleaning pad that will not scratch the acrylic surface of your tub.

Cleaning the Cover

Use a cover care product at least once per month. Find one that has UV protection and is good for cleaning and conditioning your cover.

Other Important Stuff

The following items are important too.

Shock Oxidizers

This is a very useful product that oxidizes the water and helps to get rid of organic matter like dead skin, skin oils, cosmetics and lotions. Shock oxidizing your hot tub once a week starves bacteria and helps prevent cloudy water and a clogged system. It's much better than the shock you can get from the expense that comes with not using it and creating bigger maintenance problems.

There are two types of shock, non-chlorine shock and chlorine shock. Both are good maintenance products to oxidize your spa.

For fresh water fills, use a chlorine shock. Chlorine shock is a sanitizer and will leave chlorine residual, which is critical to a clean, safe spa. A non-chlorine shock works great once you have an established a residual of chlorine or bromine in the spa as it can oxidize organics in the water without increasing your sanitizer residual. It also allows you to use the spa soon after treatment. Be sure to follow chemical manufacturers' instructions for proper use.

Neither chlorine nor non-chlorine shocks are compatible with a biguanide system. The biguanide system uses a hydrogen peroxide oxidizer to eliminate organics and does not require shocking to maintain sanitizer efficiency.

Water pH:

What is pH? It is a measurement of the concentration of hydrogen ions in your hot tub water. Without getting into a chemistry lesson, let's just say that pH is important because if you don't keep the pH levels within a small range (7.2-7.8), your water can become too alkaline or too acidic. If your pH is too low (less than 7.2), the water is too acidic and it can corrode parts of your hot tub and irritate your skin. If your water is above 7.8, it is too alkaline which can cause "scaling" from minerals and metals in your water forming deposits and possibly stains on your hot tub's acrylic surface. So, how do you know if your pH is in the right zone? First you need to test your water using a test strip. Then, use pH additives to achieve the right pH balance. When you change your water, you can add a pH product that will help prevent you from having to use any pH balancing agents until the next time you change your water.

Calcium Hardness

If you live in an area with particularly "hard" or "soft" water, it's worth checking your water calcium levels with your test strip and adjusting them if necessary. You can adjust your calcium levels up with a calcium increaser for water that is low in calcium. If the calcium level is too high you can adjust the pH and alkalinity to their lower ranges to help avoid cloudy water and scale.

Alkalinity control

Total alkalinity refers to the ability of the water to resist changes in pH. Controlling alkalinity can help keep your pH in the appropriate range thereby lessening the need for pH balancing. If your test strip indicates a need, you can lower alkalinity using a pH reducer (just like lowering your pH only you'll use more of it). Or, if you need more alkalinity, you can use an alkalinity increaser.

Heavy Metal

Some local water contains unusual amounts of iron or copper. A greenish tint in your water may indicate the presence of these metals. If this is the case in your area, resist the temptation to file for mining rights. These pesky metals can, among other things, stain your hot tub shell, increase your sanitizer consumption or foul your tub's water heater. Fortunately, you can control metals by using an additive when you change your water. Follow the manufacturer's instructions when using metal-removing products. You will probably need to add this product each time you add make-up water or refill your hot tub. Be sure to clean your filter after using the product or you may have to use a metal removing product on a weekly basis.

Spa fragrance

Use at your own risk. Since we do not know what is in them, we do not recommend using fragrances.


Compatible, but may not solve the problem. Defoamers only change the water surface tension and hide, rather than correct, the problem. Foam is caused mainly by detergents (soaps) but by many other sources too, like: soft water, body lotions and suntan oils, tile cleaners, high Total Dissolved Solids levels, air pollution, body fats secreted by the sweat glands, oils from the skin, etc. Water should be drained and replaced when total dissolved solids exceed 1,500 ppm. Using a shock may reduce the organic solids (oils, lotions, etc.) and help reduce the foam, but will have little affect on inorganic materials like calcium.

Air is good

The introduction of oxygen in to the system enhances the efficacy of the ecoONE® system. Leave your jets and air intakes set to the "on" position between spa uses.

We hope our "Intro to Hot Tub Chemicals" has cleared up a few things for you. The main thing is to be aware of the fact that a hot tub does not maintain itself. It's up to you. Meanwhile, please let us know if you have any special tips or ideas for this section that we might use in the future.