There
are common misconceptions about alternatives to chlorinated pools. Many
are turning to salt water pools in a belief that it will be less
expensive and lower maintenance. These assumptions are totally false.
If it is sodium hypochlorite pool you desire, you can save money, many
headaches, and a great deal of time by just using bleach. Bleach is
usually 6% sodium hypochlorite.
Salt water chlorinators, also known as salt water generators (SWG)
works by using electrolysis to release chlorine gas from the salt in
your pool water. Two to five hundred pounds of salt is added to the
pool water to achieve a saturation of approximately 3200 parts per
million. The salt water is then passed though a chlorinator cell that
is electronically charged and this process releases chlorine gas from
the salt. The chlorine gas then combines with the pool water to create
liquid sodium hypochlorite chlorine (more technical hypochlorous acid
and hypochlorite ions). A saltwater pool is a sodium hypochlorite
chlorine pool rather than calcium hypochlorite pool. The difference is
that you make the chlorine yourself.
If you are considering such a salt water chlorinator, there are a few
things you will want to be aware of before you buy. Many pool stores
and builders tend to only mention the pros of these units. You should
know what common problems usually arise and the reason for them so you
can avoid unnecessary disappointment with this new investment.
This list will help you recognize some of the most common problems with salt water chlorinators:
1. Corrosion
2. Degrading of coping and decking
3. Salinity killing grass, plants, and flowers (and pets?)
4. Balancing the Water chemistry
Corrosion
For those that are fortunate enough to live on the coast have
unfortunately also witnessed what salty air can do to window screens,
sliding doors, and furniture. The same hold true when you have a
salt water pool in your back yard. Anything that is metal is
susceptible to this type of carrion atmospheric corrosion. This
would include chain link fences, wrought iron gates, furniture, doors,
screen, sheds, and even lawn equipment stored close by.
Salt spray and airborne saltwater droplets introduce chloride ions
(which does come from the salt in the pool) to metal surfaces with a
corresponding deleterious effect on the metal. The presence of moisture
is an absolute necessity for most corrosion processes and when combined
with elevated temperatures and salt or pollutants further enhances the
atmospheric corrosion process.
Atmospheric corrosion is everywhere and is responsible for more metal
damage than any other form of environmental corrosion. But
this type of corrosion is exponentially elevated when a salt water pool
is in one’s backyard. Since these chloride ions can carry up to 7
miles, one could be putting their immediate neighbors at risk as well.
Degrading of Coping, Decking, and Equipment
The salt itself from a salt water pool has issues of attacking the
cement in the plaster and deck materials. This is a relatively
slow process as the salt levels are low. If the sodium
hypochlorite levels are too high, the main problem can be the corrosion
by the chlorine being produced by the electrolytic cell. Chlorine can
bleach the reagents, giving you a "false negative", and people can
grossly over-chlorinate their pool damaging equipment, the pool
surface, lighting fixtures, and ladders.
A common problem is corrosion at the ladder. The deck anchors are
usually cast aluminum and the ladder is usually stainless steel. These
dissimilar metals with the addition of the electrolytes in the water
create galvanic plating or corrosion. The saltwater will corroded
the anchors overtime.
Everyone should be aware that if you have salt water (in the 2800 ppm
or more range), you should be prepared to seal your coping, especially
if it is porous like limestone. Otherwise, the salt will dry and start
to etch into your coping. Besides sealing the stone, it is also
advisable and an added precaution to hose down the coping at the end of
any swim day with fresh water. Although the salt-water in the pool is
not corrosive at levels of up t0 3000-3500 ppm, when that water hits
the coping and evaporates, it leaves pure salt behind. The pure salt is
corrosive and is probably the cause of the corroding coping.
Some pool builders are now refusing to build any salt water pools with
cream limestone or taupe coping. Any customer that wants either coping
for a SWG pool must usually sign a release form. Pool builders have
said that they have had to replace a significant amount of both these
types of coping over the years.
Salinity killing grass, plants, flowers, (and pets?)
Most of the grass, trees, shrubs, and flowers do not grow well with
high salinity water. In fact, it can easily kill them. The
issue with grass being killed around salt water pools is very
common. When a heavy rain occurs, the elevated water level will
seep underneath the coping and run into the yard. This water will
contact a very high amount of both sodium and chloride and can kill
grass. The same scenario would affect planters located around the
pool. This can be very unsightly, much less costly, to the
homeowner.
Salt water will be harmful for pets to drink. In fact, it can lead to dehydration and serious health problems.
Problems maintaining a balanced water chemistry
• Many complain about the inability of reaching the
desired chlorine level. This may be caused from the pool pump/filter
not running long enough for the unit to create the needed amount of
chorine. The factors that increase chlorine demand are: heavy bathing
load, sunshine, hot weather, and low stabilizer level.
• If the salt level is too low, then the unit will not produce enough chlorine.
• If the stabilizer (Cyanuric Acid) level is too low,
the chlorine will not stay in the pool water long and the unit will not
be able to keep up with demand. This is very common. Many problems
occur when the stabilizer (Cyanuric Acid) levels are too low. 80ppm is
recommended by most manufacturers. In humid climates, as much as 120m
ppm may be necessary to keep the chlorine in the pool. If stabilizer
levels are too low the chorine produced will be burned off by the sun.
Conditioner acts as sunscreen for your chlorine. You may damage the
pool's interior surface with high levels of Cyanuric Acid. High levels
of stabilizer will also cause your skin to itch.
• If salt level is too high, the cell might be
failing and thus giving a faulty salt reading. The cell may indicate to
add salt. If this is done without double checking the true reading, you
can over-salt the water. Most systems will not work if the salinity of
the water is too high or too low.
• If phosphates are present in the water (stain
removal products on the market are loaded with phosphates), they are
food for algae. Some may disagree about these products and say they
have no effect. We have seen this on a regular basis and have the water
analyses that tell otherwise. If phosphate levels are too high, your
salt water chlorinator will act as though it is not creating chlorine.
When the chlorinator creates the chlorine, it immediately has to fight
off the algae that is growing, even when it not visible. When this
happens, your pool cannot catch up and build a reserve of chlorine in
the water. (1-3ppm)
Common Myth 1.
One does not have to worry about pH with a salt water chlorinator.
The Truth - When your pH and alkalinity get out of balance, your
chlorine is much less effective. The pH should be 7.4-7.6. Chlorinating
with a salt water chlorinator is similar to chlorinating with liquid
chlorine-- they both have a high pH (11.7). One common problem is that
homeowners tend not to test their pools' pH and alkalinity enough. The
main reason for this is that too many builders and retailers sell these
systems as a "set it and forget it" solution. Most people with salt
systems will run their pH from 7.8-8.0. This is bad for two reasons: 1)
the pool is in a scaling mode, and 2) the chlorine is shrouded by the
basisity of the higher pH. It is best to run between 7.4-7.6 when using
chlorine.
Common Myth #2.
One size fits all.
The Truth - It is very important when buying a chlorinator to oversize
the unit for your pool. You are better off having a chlorinator too
large for your pool than too small. A chlorinator too large can be
turned back or run for less time each day, making the cell last longer.
A unit too small will mean algae problems later on if you don't run it
for longer periods each day or add extra chlorine (no, not salt) on a
regular basis.
Common Myth #3.
There is no maintenance on a salt water pool.
The Truth - All salt water generator cells require cleaning. This must
be carried out before the calcium build up within the cell housing
becomes one big block. If left for too long, it will do two things:
• Break the cell housing.
• Shorten the cell life.
It is also very important to watch your salt level in the pool. A low
salt level (less than 2000 ppm) will cause oxygen production and damage
the platinum group metals on the anode, therefore, shortening the life
of the cell. It is recommended that you try to keep the salt level at
the higher end of the manufacturer's scale for you model. Care must be
taken not to exceed the maximum output of the power pack, as this can
damage the rectifiers and transformer.
As with any pool, one MUST maintain a proper pH. Also Cyanuric Acid
levels must be maintained or the chlorine will quickly dissipate out of
the pool.
