There are eight primary components that determine if your water chemistry is "balanced". Understanding each of these components and how it factors in to achieving balanced water is important information that every pool owner should posses. These components also dictate whether you need to add chemicals to balance your water, and what those chemicals should be. Below I will discuss each of these components, in the order you should address them.
The components of balanced water:
- Calcium Hardness
- Cyanuric Acid
- Total Dissolved Solids (TDS)
The easiest way to understand each chemical and how it factors into water balance is to use a dosing calculator. Orenda has a great calculator here
. Orenda also makes great chemicals that are professional strength and are
I always recommend keeping a spreadsheet with columns for your chemistry readings and rows for
the chemicals you add to keep as a reference for the future.
First a couple of things to consider...
Your fill water and what's in it. Knowing what you fill your pool
with is just as important to know and understand as the eight components of balanced water. Determining if it is soft or hard
will help you understand why your chemistry may or may not change quickly after
you add a lot of water in the summer. You should also be cognizant if you get
rainfall in abundance which can alter pH and alkalinity, as well as wash iron and phosphates into the water.
What you use for sanitizer and shock. The type of sanitizer you use is important as some are acidic and contain cyanuric acid (stabilizer) and / or calcium. Salt water pools have unique balance issues that require a different understanding.
Calcium hardness determines
whether water is soft and aggressive or hard and scaling. Ideal calcium hardness is 150 to 250 ppm, with the maximum at 800 ppm. Hardness below 150 ppm is considered soft water and above 400 ppm is considered hard water. Think of hardness as a beast that is hungry. If it has an empty stomach, low hardness, it wants to eat
something to get nourished. What it wants is something easy to digest like pool
plaster, liners and soft metals like copper heat exchangers. If the beast has been fed
too much it becomes heavy and wants to shed some pounds. This would be scaling. Calcium
hardness is pretty stable and doesn't change radically. It is most affected by water splash out and the use of calcium hypochlorite chlorine in the form of powder or granular. If you have high calcium in your fill water you will need to "compensate" with the alkalinity and pH in order to balance your water.
Increase calcium hardness (if your water is soft) with the use of a granular or powder form of calcium chloride.
Decrease calcium hardness (if you water is too hard) by draining water from the pool.
Alkalinity & pH
Alkalinity is water's ability to
buffer acid. pH is the measure of how acidic water is. Together, alkalinity and pH are THE balance that you will test and adjust on a
regular basis. Think of alkalinity as a
balance beam and pH as what you do to each side to keep it level.
pH is measured on a
scale from 0 to 14. 0 to 7 is the acidic side and 7 to 14 is the basic side.
Our body's natural chemistry is about 7.2 to 7.8. This is also the zone where chemicals
work best, so keeping the balance on the basic side is your goal. Ideal water alkalinity is 100 to 120 ppm. You'll want to keep the water alkalinity at 100 to 120 ppm. Once you get alkalinity in this ideal range keeping it there is easy if you check your chemistry often. Be mindful that replenishing water from splash out, as well as torrential rains can alter alkalinity quickly.
When pH falls under 7 water starts to sway the balance to the acidic
side. If yous alkalinity is below 80 ppm and the pH is under 7 you get into the
danger zone. As alkalinity decreases, the water's ability to absorb
acid declines. In order to get the pH balance back you need to increase the alkalinity.
Once the alkalinity gets back to the 100 to 120 ppm range the more stable pH will
be. Don’t be fooled by a high pH with a low alkalinity. You MUST balance
The danger zone!
Low calcium hardness with low
alkalinity and low pH creates a very hungry monster. This situation will etch
plaster, bleach color from liners and dissolve heat exchangers in heaters.
Swimmers will complain about itchy skin and irritated eyes. Shut down the pool
until you get the water balanced.
Cyanuric Acid/ Stabilizer
readings for Cyanuric Acid (CYA) is 30 to 50 ppm. Stabilizer protects chlorine from the sun. When stabilizer reaches toward
100 ppm it can have an effect on alkalinity. This means if you have a
stabilizer reading of 100 ppm and an alkalinity of 100 ppm, the actual alkalinity is
70 ppm. Your alkalinity test will state 100 ppm but it is actually 70 ppm. This situation creates aggressive water. CYA or stabilizer is a hidden
chemical in stabilized chlorine products such as trichlor tablets, dichlor
powder and granular shocks. The belief that more stabilizer protects chlorine better is not accurate.
To reduce CYA / stabilizer you must drain the pool. Hard water with high cyanuric acid is an indication to drain the pool and start fresh.
Total Dissolved Solids
TDS or Total Dissolved Solids
is all the “stuff” that is dissolved in solution. While calcium can be a large
component, organics, inorganics, cyanuric acid, sanitizer and
phosphates can be contributors. A low TDS allows your sanitizer to work more
effectively. A high TDS can cause scaling which can plug heaters. Think of a
room filled with colored ping pong balls floating around with each color a
chemical. Every time you add something to the water you add more ping pong
balls. Eventually balls start colliding with each other trying to move. If
chlorine is one color and bacteria is another, chlorine has a much more
difficult time getting to the bacteria. While there is no ideal range for TDS
the maximum is usually 1,500 ppm over the fill water.
High TDS with high calcium
hardness and high alkalinity makes water really hard and basic. This can result
in scale formations on tile and walls, and can damage heaters. The only way to remedy this situation is to drain the pool, no questions to ask, just drain it.
There is a theory that
phosphate levels over 200 ppm promote algae growth. Because many fertilizers contain
phosphates it is believed it is the source of food for algae. Get rid of
phosphates you eliminate the food supply and algae doesn’t live. Phosphates may be in
your source water, especially if you live in a rural area and use well water to fill your
pool. Another source is runoff from planters or lawns due to heavy rains.
Phosphates are be easily controlled by a phosphate remover. Orenda CV-700
phosphate remover and an enzyme that helps break down organics while it
phosphates. A single dose may rid your pool of phosphates for the season.
Maintenance dosages throughout the season is a good strategy especially if you
have phosphates returning to the pool.
While not on the balance list, metals such as iron, copper, silver and manganese can be present in your water as ions. Metal ions
are dissolved metals in solution. When
these ions combine together they form a solid that falls out of solution and
stains surfaces. Metals can be kept in
solution by using a metal treatment, chelant or sequestering agent. Overdosing
sodium carbonate can promote this ion accumulation. This may result in no metals in solution as
they have combined and fallen to the floor.
Ideal free chlorine is 3 to 5 ppm, with 2 as the minimum and 10 as the maximum. Chlorine's efficiency can be
accentuated or reduced by the many factors listed above. By keeping your stabilizer, TDS and calcium hardness low you allow chlorine to breeze through the room of ping pong balls with ease killing bacteria and oxidizing organics and inorganics.
Combined chlorine or chloramines, indicate ammonia in the water. Chloramines cause eye and skin irritation especially with low pH. What you use for a sanitizer may effect pH and alkalinity. Salt water pool chemistry will increase the pH and alkalinity.
pH also has an effect on the killing potential of chlorine. A pH of 7.0 will
allow about 80% of your sanitizer to be active with 20% in reserve. While a pH of
8.0 puts your sanitizer at about 20% active with 80% in reserve. Keeping your
pH a bit high and adding a few more ppm of sanitizer can yield an acceptable
amount of active sanitizer and allow a buffer. This will not cause adverse reactions from your swimmers as the pH and alkalinity are more in
line with the body’s natural pH balance.
To reduce chlorine use the chlorine reducing agent sodium thiosulfate. This is not recommended unless you have residuals exceeding 20 ppm as it will eliminate all the the chlorine.
While bromine is not one of our core eight contributors to balanced water it is worth mentioning because it is an excellent sanitizer. Bromine has some outstanding benefits not only in hot water applications like spas and hot tubs, but indoor pools as well. The ideal bromine reading is 2.0 to 4.0, with 6.0 being the maximum.
Temperature is not a huge
factor but it is something to consider for your pool
and especially a spa. With a calcium hardness of 200 ppm, alkalinity at 100 ppm, and pH in the 8.0 - 7.1 range, temperatures from 40 degrees all the way up to 140 degrees still maintains the balance within specifications.
What does happen in warmer waters is the
demand on the sanitizer to kill bacteria and oxidize contaminants increases. The warmer
the water, the more swimmers excrete body oils, sweat, dead skin and lotions.
This puts a higher demand on your sanitizer the warmer the water. In spas and hot tubs this gets extreme. After just 15 minutes with only two people in the water, the average residential spa will see a complete reduction of sanitizer if there is no means of administering sanitizer continuously. When you consider chlorine starts to gas off from the
water at close to 106 degrees you can see why people complain of stinking water
with watering eyes and itching skin.
Salt Water Pools
systems have a unique balance issue.
When the cell is energized and salt water travels between the plates,
sodium chloride (salt) gets split into chloride / chlorine and sodium hydroxide. Sodium hydroxide has a pH of 13 which drives the
water balance to have a high pH and alkalinity. Salt water pool owners will have the reoccurring task of keeping pH and
alkalinity down. Strategies to reduce
the alkalinity to 100 ppm and maintain low levels helps the system to work
efficiently. If the balance is allowed
to have high alkalinity and pH, the sodium hydroxide forms and falls out of
solution onto the pool floor as a white flake or powder. This condition also causes the cell plates to
form scale and plug up.
adds to TDS, but it’s a good TDS because it is sodium chloride and not junk. With this in mind, salt water pool owners
should deduct the salinity from the total TDS reading to determine what the real
TDS actually is. All of the other target chemistry ranges apply, including when to drain the pool.
Keeping the salt
content at its recommended level is critical for salt systems. Salt reduction comes only as a result of
splash out or backwashing the filter.
Each of the elements described above
hold value in the overall balance of your water. You do not necessarily need to know what they
are, all you have to do is get accurate readings from your water and plug them
into an index calculator like this one
The main items you
need to pay attention to are water hardness, TDS, alkalinity, pH and stabilizer. Water
harness doesn’t change very quickly so a reading once every several weeks may
be good for you. The same goes for TDS. Unless you start dumping a bunch of
stuff in your pool, it too is pretty consistent. That leaves stabilizer,
alkalinity and pH. I provide the parameter for stabilizer and it will increase
with the type of sanitizer you are using so a reading every couple of weeks
should show you where you are at. It only really changes when there's splash out,
backwashing, or removing water from the pool. That leaves alkalinity
and pH. That’s two things to control. Balance alkalinity first and pH will fall
into place. Adjust pH with a bit of acid or bicarbonate and your water is
great! Those dosages can be determined with a quality test kit like the Taylor K-2005
or LaMotte 7-Meter Test Kit
. Something a pool owner who takes care of their pool should have. Salt water pool owners should have test strips to test their water weekly.
You should now be ready to go out there and balance your pool water! But if you have any questions, feel free to give us a call. We're open seven days a week and welcome your questions -- (888) 836-6025.