Hot Tub Water Chemistry

If you have not yet purchased your hot tub the IHTA strongly recommends that you select a company that provides ongoing support for answers to maintaining, using, and caring for your hot tub. The following briefly outlines the 7 simple steps in keeping your water crystal clear and healthy, followed by a more detailed explanation.

• Each time you fill your hot tub test your water hardness level while the water is still cool.
• Once your water reaches temperature balance your water by testing and correcting your alkalinity level first and your pH level second. Always remember to check your pH and alkalinity levels regularly because in some water environments they have a tendency to change.
• Add whichever sanitizer you choose in accordance with the manufacturer’s instructions. This is important to keep your water free of bacteria.
• Add a mineral protection agent to protect your spa from high levels of iron and/or copper to prevent staining and scaling which would cause harm to your spa components and discolor your water.
• Add a clarifier to your water each week to both eliminate contaminants and keep your water crystal clear.
• Clean and/or replace your filter when required.
• Always keep your hot tub covered when the spa is not in use. It helps to keep your water clean and provides a safe water environment. Also remember to use a conditioner on the vinyl exterior to extend the life of your cover.

IMPORTANT: When adding chemicals always make certain your filtration pump is operational and always wait 30 minutes between adding in different chemical products.

Simple Conversion Table: 3 Teaspoons = 1 Tablespoon = 0.5 ounce

1. TESTING WATER HARDNESS

The first step to proper water chemistry is testing the hardness of your water and unfortunately it is the one step that is most neglected. The hardness of your water is determined by the calcium level. Too much calcium (common in well water) could cause scaling and too little could cause excessive foaming in your water. Calcium levels should be maintained between 200 – 400 ppm.The use of a test strip is the simplest and easiest method for testing hardness levels. The ideal time to test your water is immediately after you fill your spa when the water is still cool. Most products on the market available for raising calcium levels work more efficiently in cool water versus hot water. It is recommended to test the hardness level each time you introduce fresh water into your hot tub.

There are a variety of products on the market that will allow you to raise the calcium level in your water if you have soft water. When correcting the calcium level in your water remember to wait 2 to 3 days before retesting since most of these products take a long time to dilute. If you find that you have added too much calcium increaser drain 6 -12 inches of water, refill, and retest.

There are no chemical products available to lower your calcium level. In areas with very hard water it may benefit to run your “fill water” through a water softener (this is not recommended under any other circumstance). Other remedies are drain 12” of water, refill and retest and hope to get lucky or call for delivered water making certain the new water has a hardness level between 200 – 400 ppm. If you are unable to lower the hardness level than always make certain your pH and alkalinity levels are in balance and liberally use a mineral protection agent to protect your hard water from scaling.

2. BALANCING YOUR WATER
Balancing your water is the term that refers to keeping your pH between 7.2 to 7.8 ppm and your alkalinity between 80 to 120 ppm. Maintaining proper pH levels are highly important. If the pH level is below 7.2 ppm the water is too acidic which could corrode your spa components and also cause an irritation to your skin. A pH level above 7.8 could cause scaling and possibly stain your spa shell surface and also damage your spa’s components.  The use of specially formulated test strips for hot tubs makes keeping your water safe and crystal clear effortless. Always be sure to correct your alkalinity level first and then your pH level. Total Alkalinity helps stabilize the pH by providing a resistance of changes in your pH levels.

Why do I need to correct my pH/Alkalinity constantly?
Almost everything can cause the pH level to change; Example: spa usage raises the pH level whereas adding chlorine lowers it. Alkalinity can also change when you add water.

How do I raise alkalinity first when using a product that combines raising or lowering pH and alkalinity in the same container.
RAISING PH/ALKALINITY
To raise alkalinity run the pump on high speed and add one ounce for every 10 ppm in a 500 gallon spa. Add as much as required at one time to raise water to the correct alkalinity level. If the pH still needs to be raised once the alkalinity is in range add only ½ ounce at a time, then wait 30 minutes, test again and add accordingly, never adding more than ½ ounce each time.
LOWER PH/ALKALINITY
To lower alkalinity without lowering the pH level run the spa on high speed and add one ounce for every 10 ppm in a 500 gallon spa in just one area of the spa. When lowering alkalinity add as much at one time as necessary. . If the pH still needs to be lowered once the alkalinity is in range add only ½ ounce at a time throughout the surface of the water, then wait 30 minutes, test again and add accordingly, never adding more than ½ ounce each time.

What should I do if I have High Alkalinity and a pH below 7.0?
Drain 6 to 12” of water from your spa, refill, and retest.

Why is the pH level higher in my spa than in my pool, or when I test it from source water?
Warm water maintains a naturally higher pH level.

Is it better to have the pH read on the low or high side of 7.2 to 7.8? Chlorine prefers a lower pH level (7.2 to 7.5) where bromine works equally well throughout the entire range of 7.2 to 7.8.

3. CHOOSING & USING A SANITIZER

It is highly important to use sanitizers in your water to kill the unwanted bacteria that grow in warm water environments. And there are many choices to choose from.

CHLORINE
Chlorine is the most commonly used sanitizer for both swimming pools and hot tubs. It is also the fasting acting sanitizer for correcting aggressive water problems in hot tubs so no matter what sanitizer you choose it is recommended to have chlorine on hand to shock the water if ever needed. Chlorine is available as a Trichlor (slow dissolving chlorine recommended for swimming pools) and Dichlor (quick dissolving chlorine recommended for hot tubs). The most common mistake hot tub owners make is using chlorine for pools in their spas which can cause many problems including invalidating your spa’s warranty.
MAINTENANCE PROGRAM:
After you fill your spa you should always maintain a 1 to 3 ppm level of chlorine. To initially raise chlorine level add ½ teaspoon for every 100 gallons. Example: add 1.5 teaspoons for a 300 gallon spa and 2 tablespoons for a 1200 gallon swim spa. Chlorine should be added after every use and 3 times a week when the spa is not in use. The use of a non-chlorine shocking agent and/or an Ozonator can allow you to lessen the amount of your chlorine usage.

I’m using Chlorine but I can’t get a reading even when I add more chlorine, but my spa water is crystal clear
There are 4 choices you can take:

• Drain 6” to 12” of water from your spa, refill and restart the chlorine process.
• You can do nothing as long as your water is clear with no scent, the mineral and hardness levels are in line along with pH and alkalinity. Your primary concern is that your hot tub water could potentially get cloudy, green, and/or stale. If that occurs correcting the problem would require draining your spa.
• Super Chlorinate your water with 3 times the combined chlorine reading of the spa water, or 3 times the recommended dosage of chlorine, leave the cover partially open, make certain your filtration pump is on high speed for a minimum of one hour, and wait 24 hours before testing and reentering your spa.
• Super Shock your water with 3 times the recommended dosage with a non-chlorine shocking agent , leave the cover partially open, make certain the pump is on high speed for a minimum of one hour and wait 4 to 6 hours before testing and reentering your spa.

BROMINE:
Bromine is commonly used in hot tubs because it doesn’t gas off in temperatures above 98 degrees, but is not allowed for sale in most European markets. Bromine can be added to spa water in the form of tablets (most common application), granules, and nuggets or as a liquid in the form of sodium bromide.

BROMINE TABLETS are the easiest method of adding bromine to your water and require the use of a floating bromine dispenser which should be removed when you use your spa and replaced upon exiting. Some hot tub models offer a powerful independent 24/7 pump and a hidden weir skimmer basket to hold your bromine tablets which will sanitize more volume of water more frequently and does not require any removal and replacement during usage. Bromine tablets contain approximately 40 to 50% chlorine content so it’s not the solution for those allergic to chlorine or for those seeking to eliminate a chlorine scent. Most complaints of discoloration of bathing suits and hair are the culprit of bromine tablets so when using a floating dispenser it is recommended to only add a few tablets at one time.

SODIUM BROMIDE is often referred to as a two-step process because it needs to be activated with an oxidizer such as chlorine or most commonly with a non-chlorine shock (Potassium Monopersulfate). This two-step process requires a little more effort and is more of a learned process for those initially selecting this method of a sanitization.

MINERAL CARTRIDGES
Mineral cartridges are slow activating systems that are installed either in the filter cartridge or in a floating dispenser. Most mineral cartridges last up to 3 months before requiring replacement and are an effective method of sanitizing your water. It is often recommended to use mineral cartridges in conjunction with chlorine, bromine, or a non-chlorine shock (Potassium Monopersulfate). They are becoming popular with hot tub owners because of their ease of use and because they lessen or eliminate the amount of chlorine and/or bromine required.

What is the benefit of using Potassium Monopersulfate
This non-chlorine shock agent reduces the use of sanitizers by doing some of the work of chlorine and bromine by oxidizing contaminants and requiring the chlorine or bromine to simply do the sanitizing. It also can be used in replace of a sanitizer when used with a mineral cartridge though it is still often recommended to add small amounts of chlorine weekly to assure proper sanitization and allow for accurate testing of your water. 

OZONE
Ozone is a powerful oxidizer that is very affective in keeping your spa water free of unwanted bacteria, mold, spores, and viruses in your water. Over 90% of the bottled in the US is purified with Ozone. A product called an “Ozonator” is available on many hot tub brands. It is an excellent product to assist you keeping your water healthy and clear. A standard Ozonator that feeds ozone gas into the water produces “off gasses” should not be used on indoor spas unless the room is properly vented. Safer systems are available that sanitize the water in an independent holding tank under the cabinet and resend the sanitized water back into the spa. By eliminating the gas it allows higher levels of ozone to be used, more aggressively reducing the chlorine/bromine usage and makes it safe for indoor installations.

Can I use an Ozonator and eliminate using any sanitizer; chlorine or bromine.
No. Though ozone works 3000 times faster than most standard sanitizers and is compatible to be used in conjunction with them all, it is still only an oxidizer and requires the additional use of a sanitizer to properly protect your water’s chemistry. 

4. PREVENT STAINING & SCALING

Many local water areas (especially in well systems) contain high levels of iron and/or copper. These metals can cause a scaling to your water, stain your spa shell, damage your heater, increase sanitizer usage requirements and discolor your water. To help prevent these problems from occurring it is recommended to add a mineral removing agent (often referred to in the industry as a “Stain & Scale”) each time you add fresh water to your spa and a smaller amount each week as a preventative measure. The amount of agent you should add is dependent upon the level of mineral products your spa water contains which can be determined simply with the use of a test strip.

What is Scaling in the Water?
Scaling is a precipitation (like barnacles) that forms on the internal spa components along with the spa shell when they are in contact with water where there is a too high level of Calcium, pH, alkalinity, and/or mineral content, or an excessively high water temperature. It is highly recommended to clean you’re your spa shell immediately if scaling appears because the longer it remains the more difficult it is to remove. Since it is only the result of poor water maintenance or hard source water it is not covered by any spa manufacturer’s warranty.

Will it hurt my spa or my water chemistry if I add too much of a mineral agent?
The overuse of most mineral agents will not affect your water chemistry or hurt your spa but it is recommended to check with the manufacturer of the product you are using.

5. KEEPING YOUR WATER CRYSTAL CLEAR

Because of the hot water environment, small bacteria particles can form in hot tub water that is too small for the filter to capture. This results in cloudy and discolored water. To prevent this you should add a clarifier to your water upon the initial fill and a smaller amount each week as a preventative measure. There are two types of products on the market that eliminate small bacteria particles; a natural enzyme product and a synthetic coagulant. Synthetic coagulants bond many small particles into a larger mass allowing the filter to do its job. The negative side to synthetic coagulants is that they can be the cause of what is referred to as “scum line” along the water’s surface along with requiring more frequent cleaning of the filter cartridge.
A natural enzyme product breaks down the organics and contaminants in the water, essentially destroying them rather than joining them together with other contaminants to form a larger body. This minimizes the chance of a “scum line” forming along your water’s surface or oil slicks in the water. It also doesn’t create more work for your filter or limit water flow to your jets.   An additional benefit to a natural enzyme product is that adding too much will not ill affect your water’s chemistry whereas the overuse of a synthetic product often can. Synthetic coagulants are generally less expensive and adequate for those not experiencing water clarity problems. But for those of you constantly battling water clarity and/or those seeking a more “green” alternative a natural enzyme agent should be considered.

How Often Should I Change My Water?
The common answer voiced by all is every 90 days but it actually depends on the amount of chemicals you have added to your water. The more often you use your spa the more chemicals you use causing a rise in the TDS (Total Dissolved Solids) level. A high TDS level means your water is over saturated and your chemicals become ineffective.  Think of continuing to add a teaspoon of salt to a cup of water. Each teaspoon raises the salt content and at a certain point your water becomes saturated and the new salt merely settles at the bottom of the cup. It is recommended to use TDS test strips that provide you a simple method of knowing when to change your water which in turn will save you time, work, and money. When you change your water always remember to clean your acrylic shell with an approved cleaning product.

What Causes the Foam in Spa Water?
Common causes of foaming are laundry soap residue on bathing suits and cleaning solution on filter cartridges that have not been thoroughly rinsed, along with deodorant, body lotions, and hair products. Other causes of foaming are high levels of TDS (waiting too long to change your water), soft water, a high pH level, and poorly formulated chemical products sold at discount stores. These causes are only temporary and easily corrected but resurface shortly thereafter until the root problem is corrected. Remember foaming will not harm you or your hot tub but often the cause of foaming may affect your sanitizer level, so check it after any high level occurrence of foaming.
There are many companies that sell a product that eliminates the foam in your water. These products should be used very sparingly since overuse could negatively affect your water’s chemistry.

What causes milky water and how do I correct it?
Untreated cloudy water can become milky water. Adding ph+ to a spa with very low pH level can cause a temporary chemical reaction that creates cloudy water. Adding a Natural Enzyme clarifier and putting in a new filter will help.

When I haven’t used my spa or jetted bathtub over a period of time I sometimes get a foul order when I first activate the jets. How can I rid myself of this problem?
This is a very common problem especially with jetted bathtubs since they do not have a filter system and the water in the lines often remains stagnant breeding bacteria. It is also a problem with hot tubs that have multiple pumps and jets where they are all not required to activate once or twice a day (often referred to as a clean out system). To rid yourself of this problem you can use a product often referred to as a “jet-line cleaner”. It is recommended to be used a minimum of twice a year when you are changing the water. This product is very effective and cleaning bacteria from the lines and also in restoring the discoloration sometimes on the plastic jets inside your spa.

6. CLEAN & REPLACE YOUR FILTER

Cleaning and replacing your filter cartridge is an important part of maintaining clean and healthy water. Please refer to section titled “Filter Maintenance” for complete information.

7. KEEP YOUR HOT TUB COVERED

Covers are extremely important in keeping water clean, preventing evaporation, and maintaining a safe water environment.

ADDITIONAL COMMONLY ASKED CHEMICAL QUESTIONS
Do Chemical Products have a shelf life?
Most chemicals do not have a shelf life as long as they are kept in a temperature controlled, dry environment. Liquid chemical products that freeze-up and granular products that are hardened should be disposed of. Test Strips are the most sensitive product that have shelf life and can be damaged by being exposed to moisture and excessive heat.

Is it beneficial to purchase from a US Supplier?
Yes, primarily because many products are sensitive to temperature and humidity there is a possibility that ocean based shipments could have experienced extreme temperature conditions in their transit causing damage that may even not be noticeable to the US vendor.

Are all Chemical Products the same?
No, some internet based companies and mass merchants have diluted liquid solutions and added fillers into their granular products that save them money and require you to add more chemicals, more frequently. Beware, as well, since some of them do not even make changes to the instructions for usage on the containers. Purchasing from and IHTA member or a company you have had a reliable relationship in the past is often the safest and least expensive decision in choosing a vendor.