SPA CHEMISTRY
Basic Spa Water Chemistry
The number of chemicals related to spa water chemistry
overwhelms many spa owners. The important thing to remember is that
all you are trying to achieve is a good balance so that your spa
water is clean and comfortable for use. We recommend that you bring
in a water sample after you have freshly refilled the spa and brought
it up to the set temperature. This way, we can provide you with
a free computerized analysis to ensure that you start off right.
Every fall, Ashton Pools, Ponds & Spas hosts a Spa School Seminar
that teaches both old and new spa owners how to spend less time
maintaining and more time enjoying their spas. This is a great opportunity
to come in and ask your hardest questions to our expert guest speaker
(who is also very generous when giving out door prizes). For more
information about these seminars, speak with one of our staff.
Before we dive into the chemistry lesson, here are a few helpful
reminders for maintaining a clean and beautiful spa:
Chemicals provide balance. People sometimes misunderstand
that the primary purpose of adding chemicals to spa water is to
create healthy water. Adding chemicals to your water doesn't necessarily
create an unhealthy chemical environment, nor does it 'overchemicalize'
the water. Instead, chemicals are added in order to accomplish balanced
and safe water. Without chemicals, our spas would be green, slimy
and covered in scale– and if you had wanted to have an alligator
in your backyard you wouldn’t have spent your money on a hot
tub.
Spa chemistry is different than pool chemistry.
The differences in size and temperature of a hot tub compared to
a pool make a big difference when doing maintenance. A spa is a
much smaller container for water than a pool. Having four people
in an average hot tub is like having 160 people in an average pool.
Therefore sanitizer (chlorine or bromine) will get used up more
quickly and you will notice more abrupt changes in pH. As a result,
you will want to test and treat the water more frequently. As well,
because spa water is kept at high temperatures, it is important
to maintain a higher sanitizer level (3-5ppm for chlorine and 4-6ppm
for bromine) to keep bacteria and algae from running rampant.
Get into a routine. Perhaps the best advice given
to new spa owners is to develop a routine for chemical additions.
Find a day of the week when you’ll remember to add maintenance
chemicals like scale inhibitor and shock (ex. Sunday night). A routine
helps prevent forgetfulness and ensures consistent water treatment.
An easy way to maintain clean water is to ensure a good sanitizer
level before entering the spa and shocking weekly and after heavy
usage.
Shocking your spa: You will need to shock your
spa periodically to rejuvenate the bromine or chlorine level and
oxidize the organic wastes that build-up. It is best to shock your
spa at a time when you won’t be using it and to remove the
lid for at least 15 minutes afterwards. Always keep your pump running
so that the chemicals don’t settle on surfaces. There are
several different ways to shock a spa, such as adding a larger than
normal amount of granular chlorine or bromine, or using a specific
oxidizing product. Ask your spa water technician which method may
be better for you if you are unsure.
Heavy bather load affects water balance. Your
spa will eat up chemicals faster if it is used more frequently or
by many people. As well, skin lotions and hairstyling products can
use up sanitizer and throw off pH. It is a good idea to shock the
spa water and recheck water chemistry after heavy use.
Planning on going away? If you are going away
for an extended period of time (more than two weeks) you may be
considering draining your spa and refilling it after you get back.
With that in mind, you will want to avoid draining the spa during
cold weather, as any water left in the plumbing can freeze and do
some significant damage. Leaving your spa empty does have certain
advantages, like eliminating the chance of freezing due to extended
winter power shortages, and preventing accidental drowning. You
will need to consider all of these factors before making a decision.
If you leave the spa running, you should have someone check on
it weekly to add the necessary chemicals. The chlorine or bromine
will get used up whether you are using the spa or not. This person
can also make sure that nothing has gone awry with the spa pump
or controls, and can call a service technician if it has. You may
be thinking that it is a waste of money to leave your spa running
and be adding chemicals when you are not there to use it, but preventing
the potential problems of draining a spa in the winter will save
you some very expensive repairs.
The Elements of Water Balance
The Saturation Index
When we talk about water balance, we are measuring the relationship
between 4 factors that are key in deciding the overall healthiness
of your spa water. The Saturation Index is a mathematical equation
that measures the temperature, total alkalinity, pH and calcium
hardness of water in order to predict whether it is scale forming,
neutral or corrosive. All of these factors have a recommended range
for spa usage, and it is only when all of these factors are within
these prescribed ranges that true water balance can be achieved.
1. Temperature
A spa is typically much warmer than a pool, which makes it a better
breeding ground for bacteria. As well, higher temperatures encourage
minerals and metals to form deposits, increasing the chance of staining
and scaling in your spa. This is the main reason why temperature
is used in calculating the Saturation Index.
2. Total Alkalinity
TA is the total amount of alkaline materials (carbonates, bicarbonates,
hydroxides) present in the water. TA is a buffer for pH, meaning
that it controls the pH’s ability to change. TA and pH have
a positive relationship with one another. If the total alkalinity
is too high, then the pH will most likely remain too high and difficult
to adjust. Conversely, if the total alkalinity is too low, the pH
will stay below respectable ranges and fluctuate excessively. The
acceptable range for TA in spas is 125-150ppm.
3. pH
pH is the measure of the water’s acidity or basicity (alkalinity).
The pH scale measures from 0 to 14, where a pH of 7 is neutral.
A low pH can cause faster sanitizer loss, eye and skin irritation,
as well as corrosion of spa surfaces and fixtures. Water with a
high pH can be cloudy and scale forming, and will also reduce sanitizer
effectiveness. The acceptable range for pH in spas is 7.2-7.6.
4. Calcium Hardness
CH refers to the amount of calcium dissolved in the water. Water
that is low in calcium can aid in the corrosion of the spa heating
element, the plumbing and the spa surfaces. Water high in calcium
has a tendency to form scale; thus, damage to plumbing, filtration,
heating elements and spa surfaces can result. Very hard water also
reduces chemical effectiveness. The acceptable range for calcium
hardness in spas is 100-200ppm. When calcium hardness is too high,
the only way to lower it is through dilution of water. Use scale
inhibitor regularly as a preventative measure for calcium scale
formation.
Total Dissolved Solids (TDS): Another Important Factor
in Spa Balance
Though not used in calculating the saturation index, another important
factor to consider in hot tub maintenance is Total Dissolved Solids
(TDS). Water is a good solvent: it will absorb and pick up impurities
quickly and easily. TDS is the measure of all of the dissolved materials
in water, including metals, minerals, chemicals and organic matter.
If your spa has a high TDS, it is more likely to develop a foul
odour or become cloudy. As well, chemical effectiveness is reduced
and you will end up using more chemicals than you normally would
to keep your spa clean. A freshly filled spa usually has TDS between
0 to 500ppm in Waterloo Region. Once the TDS reaches 1500ppm, it
is a good time to drain, clean and refill the spa. You can test
the TDS using test strips or by bringing a sample in for an analysis.
Common Spa Problems and Solutions
This section will cover some of the most commonly encountered spa
problems, as well as the possible causes for them. We have included
our best advice for each situation, but remember that every spa
is different, and sometimes there are two or more factors as the
root cause of your problem. Once you have more experience with your
spa, you will know instinctively how to solve it. If at any point
you are getting frustrated or confused, don’t give up: bring
a sample of your spa water in for analysis and we can help you pinpoint
where your troubles lie.
1. Cloudy Spa Water
Cloudy water is most often caused by one or a combination of the
following:
a) An insufficient amount of sanitizer in the water
b) A recently heavy bather load
c) Dirty filters
Other less common causes can be an overdose of chemicals, a very
high pH, or water that needs to be changed.
The most common cause of cloudy water is simply a lack of bromine
and chlorine. Maybe you are not adding enough, you are not adding
it as frequently as you should, or you had a lot more people in
the spa than normal but you didn’t account for it. The simplest
solution for this problem is to shock the water. If the water remains
cloudy, try a clarifying product. Clarifiers bind together all of
the small particles floating in the water, making them large enough
so that the filter can collect them. To prevent cloudiness in the
future, maintain a consistent level of sanitizer, shock the spa
weekly and incorporate a clarifying product into your maintenance
routine.
Another common cause of cloudy water is a dirty filter. Have you
cleaned your filters lately? If not, then you should remove them
and give them a thorough cleaning and a good soak in a filter-cleaning
product. You should rinse your filters about once a week, and soak
them in a filter cleaner every 4-6 weeks so that they can effectively
pull debris out of the spa water.
Sometimes adding calcium chloride (calcium increaser) at the same
time as sodium bicarbonate (alkalinity increaser) can cloud the
water even if they were added in the right dosages. Always allow
your chemicals some time to dissolve between additions.
If you think adding too many chemicals caused the cloudiness, then
you may want to do a partial drain and refill. But this depends
entirely on how these additions have affected the various elements
of water balance. Your best bet is to bring a water sample in for
analysis and talk with one of our water experts before doing anything.
2. The pH is High and Won't Come Down
If the pH is high, your total alkalinity is probably also high.
If this is the case, you will need to be patient and keep adding
small amounts of pH reducer until it comes down. If your spa has
buttons or dials to control the air being added to the jets, turn
them off when you are not using it. Sometimes the steady stream
of air being incorporated into the water can raise pH. If the problem
persists for more than a 10 days and you have been making steady
chemical additions, bring a sample into Ashton Pools for a free
analysis and some advice.
3. I Can’t Keep My Bromine/Chlorine Level Up
If you find that you are adding bromine or chlorine to your spa
but cannot reach the recommended levels (3-5ppm), you simply may
not be adding enough to the water. Bromine and chlorine get used
up keeping your spa clean and free of bacteria. Each time you want
to use your spa, you should check the level of sanitizer and add
bromine or chlorine if needed. Never get into a hot tub that has
no sanitizer in it, as there could be an excessive amount of bacteria
present. If you are using bromine or chlorine tablets in a floating
dispenser, open up the setting one or two levels and add a small
amount of concentrated granular bromine or chlorine as a supplement.
You can also try shocking the spa, which will eliminate any excess
bacteria, soaps, and oils that can hinder your sanitizer’s
effectiveness. If you use granular chlorine or bromine to shock
the spa, then add the recommended shocking dosage and retest the
water after a few hours. Immediately after shocking, the chlorine
or bromine level will be very high and you should not re-enter the
spa before it comes down below the 10ppm range. If you use an oxidizing-only
product to shock your spa (like Spa Lite), then wait the recommended
time (usually 15-20 minutes) before re-entering the spa.
Another possibility is that the spa water is unbalanced (ex. CH
too high, TDS is over 1500 ppm, pH is too low or high). You will
need to treat these issues first. Unbalanced water can make it harder
for sanitizers to do their job. Bring a sample into Ashton Pools
to rule out any of these possibilities.
4. The Spa Has a Strong Odour
A Strong “Pool” Smell: You may think
that a strong chlorine smell in your spa just means that there is
a lot of chlorine or bromine present. But in reality, an unpleasant
“pool smell” is usually a sign that there is an excessive
build-up of used-up chlorine or bromine and other unhealthy compounds.
The only way to eliminate this build-up is by shocking the water.
This will oxidize, or “burn off” the unhealthy compounds,
keeping your spa cleaner and fresher smelling. Afterwards you should
notice that your spa smells fresher and being in or near it doesn’t
burn your eyes and nose.
If your spa is balanced and the smell is still turning you off,
try using a spa fragrance or a freshener and deodorizer. There are
many different products available that are meant for use is spas
that wont affect your water chemistry.
Indoor Spas: If your spa is enclosed and you find
that the odour has become overpowering, you probably need to allow
the spa to breathe more often. Try removing the cover from the spa
one or two times a week while increasing the air circulation (open
some windows, turn on a fan). This will release the off-gases that
accumulate under the lid and get them out of your home. By releasing
this build-up more often, you will also reduce the potency of the
smell it can cause and prevent any stale chlorine odours.
A Moldy/ Mildew Odour: There are a couple of potential
sources of a mold or mildew smell in a spa. If the cause seems to
be the water itself, you probably need to shock it or drain and
refill. Another potential cause of a bad mildew odour can be water
that has gotten into somewhere it shouldn’t have, and has
been sitting stagnant for a period of time.
The first place to examine is the spa cover. Is it in good shape?
A good cleaning may be in order if you haven’t done one in
awhile. Are there rips or tears in the cover fabric? If so, this
can allow water to enter the cover and the foam inserts. Remove
the inserts so that you can take a closer look and give them a cleaning
if necessary.
If the cover doesn’t seem to be the problem, you can move
on and check the area around and inside the spa cabinet. Open up
the cabinet and do a smell check: is this the source of the odour?
If it is, look for any water or water stains. If there is a small
leak in the spa plumbing or if water has been entering the spa from
the exterior, you should fix these problems before more damage can
occur.
If your investigations have revealed nothing, but the odour is
still there, it may just be that your spa needs a good cleaning.
Drain the water and clean the spa surface, filter, cabinet and cover.
For some tips on cleaning your spa, see the Spa Maintenance section
of this manual.
Other Odours: Certain metals also have odours,
such as iron. If you suspect that metals may be your problem, bring
a water sample in and request a metals test.
5. There is a Residue Forming on the Spa Surface
If the residue is slimy and brown, most likely it is a scum line
that can be cleaned off with a spa/hot tub cleaner. Check your filters
to ensure they are in good shape, and use a preventative enzyme
based product (like Refresh), which eats up oil and dirt before
it builds up. You can also try a Scumbug or a Spa Ball left floating
in the water to manually absorb oil and reduce scum.
If the residue is white / flaky / rough, it may be calcium
scale formation. High temperatures bring calcium out of solution
to form scale, hence why our household kettle tends to be coated
with it. This can be very harmful to your heating element and plumbing,
and once present is very difficult to eradicate. A product such
as Swirl Away can be used when draining your spa to help loosen
some of the build-up, and a scale inhibitor will help prevent future
build-up. Prevention is the most important part of dealing with
scale.
If the spa surface just seems rough, but you know your
calcium hardness level is not high, then the problem may actually
be corrosion. A low pH mixed with a low calcium hardness level is
the main cause of corrosion and etching of spa surfaces. This can
be a significant problem, and should be treated immediately to avoid
any further damage. Make sure to balance your pH and increase calcium
hardness if it is low. By the time you notice the corrosion of the
spa surface, there has probably been damage done to your plumbing
components that you can’t see. Keep your eyes peeled for rust
and evidence of leaks. A surefire sign that corrosion is your problem
is that if any metal fixtures in the spa have started to rust.
Should I Use Soft Water in my Spa? If you have
had your tap water tested and know that the calcium level is very
high, the next time you fill the tub you can use a mix of hard and
soft water. This will reduce the hardness, but remember to keep
a level of at least 100-200ppm of calcium. Bring a sample of your
hard water for testing to determine how much soft water you should
use. Never fill a spa entirely with soft water, as a low calcium
level will result in etching of spa surfaces, corrosion of metals,
and foamy, cloudy water.
6. After Using My Spa, I Get Dry and Itchy Skin
Sitting is a spa can dry out your skin a great deal, especially
in the winter. You can combat this by showering after spa use and
using a good quality moisturizer to re-hydrate your skin. Using
a water-conditioning product like SpaGuard’s Optimizer Plus
in the spa water itself will help reduce dryness.
Rashes or eye irritation*: If you find that you
are developing a rash, don’t blame the bromine or chlorine
right away. The percentage of people who are allergic to bromine
or chlorine is very, very low, and many times the problem lies with
unbalanced water and sensitive skin. Water with a high or low pH
will be harsh on skin and eyes, and will be particularly irritating
to people with skin conditions like eczema and dermatitis. Balanced
spa water with a pH around 7.5 is much more comfortable and compatible
with your body.
Sometimes used up chlorine, which contains chloramines, builds
up in your spa, and can cause irritation. A chloramine problem can
be identified by a strong chemical odour in the spa and burning,
red eyes. You can quickly and easily eradicate this problem by shocking
your spa water.
Another less common possibility can present itself when there is
the right environment of low chlorine or bromine and excessive oil
and grease. A pathogen called Pseudomonas Aeruginosa can multiply
and infect the hair follicles on the body. This is just one more
reason to be diligent with chemical additions, as a lack of chlorine
or bromine in spa water is the most common cause for a problem.
The symptoms of an infection include:
- Itchy, bumpy rash occurring 8-48 hours after being exposed.
- Can appear on legs, arms or trunk of body.
- Rash disappears 7 to 10 days with no treatment.
- Occurs in several people who used the spa at the same time.
Do not use your spa until the rash has cleared up, as doing so
can just re-establish the problem or make it worse.
To get rid of Pseudomonas Aeruginosa, you should shock
the spa water, then drain and clean your spa thoroughly. While the
spa is empty, you should clean the filters and surfaces and remove
any scum lines. After refilling, shock the water and establish a
good chlorine/bromine level before use.
*Always check with a doctor if a rash or eye irritation is persistent,
painful, gets worse or if the rash starts to spread.
7. Persistent Foaming
Several different things (i.e. detergents, hair products, excessive
oils and perspiration) can cause foaming in a spa. Persistent foaming
can indicate that you are not oxidizing your spa water often enough.
Get into the routine of shocking your spa once per week, as well
as after times of heavy use. Anti-foam products will temporarily
eliminate any foam, and can be added anytime you are using the spa.
To help prevent foaming caused by excessive oils in your spa water,
use an enzyme product like Descummer.
If the foam is white and soapy in nature, it may be that some detergent
has been introduced to the spa from bathing suits or clothing. This
type of sudsing can be very persistent. You will need to shock the
spa and rinse the filters thoroughly. If you have done this several
times with no success, you may need to do a drain and refill. In
the future, do not wash your bathing suits with soap and request
that guests do the same. You should also refrain form wearing t-shirts
or other non-swimwear clothing in the spa, as these can have a lot
of soap residue on them.
Tip for Cleaning Bathing Suits – The easiest way to prevent
sudsing in your spa is not to wash your bathing suits with detergent.
If you are only using them in your spa and/or pool, then a cold-water
rinse through your washing machine will get rid of any dirt and
chemical build-up. This is also gentler on the fabric of the suits,
helping them to last longer. The sanitizer present in your spa water
will keep your suits clean, and hanging them to dry between uses
will prevent bacteria and mold from forming.
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