texas pool schol salt pools evaporation_alk_ ph_chlorine_ cya effects

© National Swimming Pool Foundation 2010 1

Texas Pool SchoolPlease turn cell phone on vibrate and ringer off

during the classThank You


United States Geological Survey Apr 15, 2014 Evaporation is the process by which water changes from a liquid to a gas or vapor.

Liquid can be sitting in one place (maybe a pool) and its molecules will become a gas. That's the process called evaporation. It can happen when liquids are cold or when they are warm. It happens more often with warmer liquids, however when matter has a higher temperature, the molecules have a higher energy. When the energy in specific molecules reaches a certain level, they can have a phase change. Evaporation is all about the energy in individual molecules, not about the average energy of a system. The average energy can be low and the evaporation still continues. You might be wondering how that can happen when the temperature is low. It turns out that all liquids can evaporate at room temperature and normal air pressure. Evaporation happens when atoms or molecules escape from the liquid and turn into a vapor. Not all of the molecules in a liquid have the same energy. When you have a pool of water (H2O) on a windy day, the wind can cause an increased rate of evaporation even when it is cold out.

This is why on windy days in the winter we loose as much or more water in a pool than in the summer.


EvaporationEvaporation in Houston Texas is 4’.311” a yearThis is an average of 1” a week.

http://www.texasalmanac.com from 1/1/07 – 12/31/2010

Water that evaporates is pure , no solid content evaporates only water.

What does this mean? It means if you are loosing salt you have a leak. 3 ways to loose salt 1) splash out 2) backwash 3) Leak

http://www.texasalmanac.com/


Water Facts

75% of the earth is covered with water. 97% of the earth's water is in the oceans, which leaves only 3% of the earth's water as fresh water. Of the fresh water, only 1% is available for use as drinking water.

Water exists in 3 forms; solid, liquid and vapor. A person can survive one month without food, but only one week without

water. The average person in the United States uses between 50 and 75 gallons of

water each day. Water is composed of 2 hydrogen elements and 1 oxygen element. H2O Water freezes at 32 degrees Fahrenheit or 0 degrees Celsius. The human body is comprised of 66% water. A person must consume 2.5 quarts per day. One cubic foot of water is equal to 7.48 gallons of water.


Salt PoolsUnderstanding the salt system is the first step.Salt is not chlorine, the generator turns the salt water into chlorine by DC electrolysis. Every 24 hours the system CAN create 1 pound or 1 gallon of 12.5% liquid chlorine (sodium hypochlorite)The key word is CAN, it must run for 24 hours and at 100%. Sodium hypochlorite is not protected from the UV rays so it will dissipate by 95% in 2 hours if not protected and the byproduct of this chlorine producing system is soda ash which raises the pH.

To sum up what I found out, here are the top five myths of salt-water swimming pools, debunked:

1. A salt-water pool is chlorine free. Salt chlorine generation is simply a different way of producing chlorine. It’s merely producing chlorine from salt, rather than adding the chlorine directly to the pool. Pool owners still have to maintain 1-4 parts per million (ppm) of chlorine in the water at all times, per EPA guidelines. If you want a pool that is completely chlorine free, you would have to use a combination of products. UV and Ozone reduce the amount of chlorine needed but can not do the job properly by them selves minerals help reduce the use need for chlorine but do not eliminate the need however when used together UV, Ozone and Minerals together eliminate the need to use chlorine when used with Borates and a VSP pump that runs 7 days a week and 24 hours a day. This sounds expensive but it can save you thousands in electricity and chemicals.

2. A salt-water pool is easier to own. Pool owners need to understand that a salt chlorine generator only takes the place of the daily disinfection requirement of the pool. It replaces tablets, sticks or whichever chlorine form you would otherwise use for pool water disinfection. Having a salt chlorine generator does not eliminate the necessary ongoing tasks of maintaining and testing pH, alkalinity, calcium and cyanuric acid. All these other water balances need to be tested and adjusted pH, alkalinity weekly and calcium, cyanuric acid every 1 to 3 months.

3. With a salt-water pool I won’t have to carry hazardous chemicals around. You won’t have to carry chlorine, but you will still need to carry Muriatic acid or other hazardous chemicals required to adjust the pH. Most of these chemicals are much more difficult to handle than modern chlorine options. A salt-water pool has a constantly rising pH, and this requires more Muriatic acid use than traditional chlorine. In addition, many pool owners don’t realize the sheer volume of salt necessary to operate a salt chlorine generator. 400-600 pounds of salt must be carried and added into the pool just to set it up. After that, the pool owner will still have to carry at least half a dozen 40-pound bags of salt to the pool every year from splash out, backwashing the filter, rain water over filling the pool or water leaks in equipment and pipes.

4. Having a salt-water pool is less expensive because you don’t have to buy chlorine.Most people save little or no money over a 5-10 year time period. The cost of buying the salt chlorine generator system, maintaining the system, replacing cells, higher electrical use and making repairs normally outweighs any savings. If you add up the costs over time, you will probably realize that a pool owner may spend more on a salt-water pool.

5. The water in a salt-water pool feels better on the skin, hair and eyes.A salt-water pool is a chlorinated pool, so any difference in the water’s feel is not due to chlorine. The perceived difference may be due to the added salt, but these added salt levels have negative affects such as accelerated corrosion of pool equipment and cement, stone and stainless steel surfaces near the pool. The same feel to the water can be obtained by borates which also enhance sanitizer performance by keeping the water balanced.

All this is manageable by understanding pH, Alkalinity, electrical rates


AlkalinityTotal alkalinity is a measure of the total amount of dissolved particles in the water and is described

as the water’s ability to neutralize acid. Total Alkalinity (TA) should usually be kept at 80 - 120 ppm.

(The alkalinity should never be below 60 ppm or above 140 ppm)Alkalinity has a significant impact on pH levels of the pool, but they are two separate entities. By

controlling the alkalinity, you can ensure that the pH level stays stable which is suggested for chlorine efficiency. It is common to see the alkalinity level of a pool rise periodically. Several common causes of high alkalinity, the amount of sodium bicarbonate is simply over estimated, the source water is high in alkalinity. Body sweat and lotions that mix with the water in the swimming pool can also lead to higher alkaline levels. One common indication that the water in the pool is high in alkalinity is when the water turns cloudy.

If the alkalinity level of the water is higher than normal levels,(80 ppm – 120 ppm) it is necessary to bring it down. For this purpose, you must add dry acid or muriatic acid to the water.

Care should be taken to ensure that the acid should not be poured near any metal fittings in the pool.

Lowering Alkalinity with Muriatic acid straight from a jug. Turn off the pumps and allowing the water to settle

16 ounces per 10,000 gallons in deep end in 1 spot lowers alkalinity 10 ppm, allow the chemicals 15 - 30 minutes then turn the pumps back on and allow the water to mix thoroughly

Caution: The lower alkalinity is the more it affects pH. Alkalinity below 80 acid will change the pH more than .2 per 10K

If you want to lower pH and not lower alkalinity much add 16 ounces of acid to a bucket of water (5 gallon bucket) then pour in 1 spot. This lowers pH .2 and Alkalinity .5 - .7 in 10,000 gallons (deep end area preferred)

Water with high alkaline levels is known as ‘hard water’.The Higher Alkalinity the higher the cost of lowering pH. When the TA is too high, the following can occur:pH keeps going up despite regular addition of pH-down (Acid)burning eyes and itchy skinreduced chlorine efficiency resulting in algae growth


Alkalinity Over View

The total alkalinity (TA) is a measure of how much of the alkaline substances there are in the water. In the swimming pool water, we are concerned with bicarbonate alkalinity, which should be between 80 ppm and 120 ppm.

When the total alkalinity (TA) is within this range, it prevents rapid pH changes and "stabilizes" the pH level.

If the TA is too low, Marbelite and plaster walls will become etched, metals corrode, the pool's walls and floor can stain, the water can turn green, eyes burn and we can have pH bounce (pH rapidly going up and down, seemingly at random).

If the TA is too high, the pH is difficult to adjust, the water becomes cloudy, the pool constantly needs acid (according to your test kit) and the chlorine loses its efficiency as a disinfectant. (Cost you MONEY)

It is recommended that you test the TA regularly, but in practice it changes very little in a well-maintained pool.

To raise the level of TA, we use sodium bicarbonate; it is the only chemical which will do this without increasing the pH very much

Lowering the total alkalinity Acid, either liquid or dry, is added to the deepest part of the pool with the filter off.


pHis the measure of relative acid concentration in the water.

pH range:• Ideal pH values 7.4 to 7.6 APSP • 7.2 to 7.4 is Better (Your Eyes pH 7.325) • acceptable pH values 7.2 to 7.8 APSP (WHY ?)• 7.2 – 7.6 is Better

Chemicals generally used to adjust pH in pools or spa. Acid, Sodium Bicarbonate, CO2, Soda Ash.


pH

pH is a value that indicates how acidic or basic a solution is. pH is one of the most important aspects of pool and spa care. “p” stands for power and the “H” stands for hydrogen. Hydrogen is the lightest element on the atomic chart of elements, pH is a measure of the concentration of hydrogen ions in the water and is the measure of relative degree of acid or base in the water. The pH scale is logarithmic meaning each whole number is 10 times greater or less than the previous number, or it takes 10 times more acid to reach your goal. A pH of 9.0 would take 10 times more acid than a pH of 8.0 to reach 7.0.

The pH scale is from 0 to 14.0 with a pH of 7.0 being neutral below 7.0 is acidic which can be corrosive and above 7.0 is base, pH above 7.8 is scale forming.


pH in Depth

The pH is one of the most important factors in pool water balance, chlorine’s effectiveness and it should be tested and corrected at least every week. pH is the measure of how acid/ alkaline the swimming pool water is. A pH of 7.0 is neutral - below 7.0 is acidic, above 7.0 is alkaline. The pH of our eyes is 7.325 . No wonder that the ideal pH for your pool is just that - 7.2 – 7.4 , and should be kept within the range of 7.0-7.6 for chlorine efficiency and eye comfort . (APSP standards 7.2 – 7.8 more on this latter)

What happens when the pool is too acidic? (pH is low)If your swimming pool is Marbelite or plaster, the pool water will begin to dissolve the surface, creating a roughness which is ideal for

pool algae growth. A similar result occurs in the grouting of tiled swimming pools.Metals corrode - and this includes swimming pool equipment, pipe fittings, pump connections, heater cores, etc.As the swimming pool walls and metal parts corrode, sulphates are formed. These sulphates are released from the water onto the walls

and floor of the swimming pool causing ugly brown, black or blueish stains.Chlorine, which is used as a disinfectant in the swimming pool water, is activated and lost to the atmosphere very quickly. The water is

not being sanitized, and we are throwing away our money by adding chlorine when the pH is too low. ( This is known as chlorine burn off)

When we swim, our eyes and nose burn. Our swimwear fades and perishes. Our skin gets dry and itchy. (Skin can breakout in red spots)What happens when the pool is too alkaline? (pH is high)The calcium in the swimming pool water combines with carbonates and forms scale, just like in our kettles. This calcification is seen most

at the waterline, where it traps dust and dirt, turning black with time.The swimming pool water starts to become cloudy or murky and it loses its sparkle.The calcium carbonate has a tendency to plate out on the sand in the swimming pool filter, effectively turning it into cement. So

your sand filter becomes a cement filter, and loses its ability to trap dirt from the pool water.As the pH rises, the power of the chlorine to act on foreign particles is lost. At a pH of 8.0 the pool can only use 20 – 24% of the chlorine

you put in. So 76 - 80% of it goes to waste and you would need 5 times as much chlorine to provide the disinfection you need.In alkaline swimming pool water, the swimmers suffer too. Our eyes and nose burn and our skin gets dry and itchy.By neglecting to test and correct the pH of swimming pool water, we not only cause it to become unsightly, but we also cause ourselves

physical discomfort. In addition to this, we insist on throwing away our hard-earned money on swimming pool chemicals that cannot possibly be effective in pool water with high pH.

After testing the water, make the goal to bring the pH to a level of about 7.2 .


Chlorine’s Disinfectant Properties

15%Kill

85%Oxidize

MicroorganismsViruses, Bacteria

ContaminantsOils, Sweat, Urine

Leave aResidual

ConcentrationFree Chlorine


Disinfection

Disinfection is also called sanitation when we shock 15% of what we are doing is disinfection.

Disinfection is the process of destroying organisms that are harmful to people


Oxidation

The process of changing the chemical structure of a contaminant thus helping remove it from the water


Chlorine Chemistry

Hypochlorous acid, which is the active killing form of chlorine in waterHypochlorite ion, which is an inactive form of chlorine in water

HOCl OCl– + H+

HypochlorousAcid

HypochloriteIon

HydrogenIon

pH Dependent

XClAny form

of chlorine

H2O HOCl By-productWater Hypochlorous

AcidSpecific to thetype of chlorine

++


Hypochlorous Acid

pHdependent

8.5

8.0

7.8

7.5

7.2

7.0

6.5

6.0

9

24

33

50

66

76

91

97

pH% HOCl


Chlorine Compounds

Unstabilized (inorganic) chlorine• calcium hypochlorite• sodium hypochlorite• chlorine gas

Stabilized (organic) chlorine• Contain cyanuric acid as

part of the compound• Dichloride / Trichlorine


Chlorine: Use per 10,000 Gallons

Chemical to treat / Desired Change 1 ppm 5 ppm 10 ppmCalcium Hypochlorite 65% - 68% 2 ounces 10 ounces 1.3 pounds10% Sodium Hypochlorite Liquid 12 ounces 64 ounces 1 gallonDichloride 56% 2.4 ounces 12 ounces 24 ouncesTrichlor Granules 1.5 ounces 7.5 ounces 15 ounces


Use of stabilizers • Stabilizers decrease the breakdown of

chlorine due to UV light Stabilizer for chlorine is cyanuric acid

• The ideal range for cyanuric acid levels is 10-25 ppm for chlorine pools 20-30 ppm for salt pools.

• Commercial pools are not allowed to have over 50 ppm as of Sept. 2012


Cyanuric Acid Down SideBy forming temporary bonds with the free chlorine,

cyanuric acid will reduce the overall effectiveness of chlorine.

The amount of time it takes to kill bacteria lengthens as the concentration of cyanuric acid increases. For this reason, the LincolnLancaster County Health Department recommends that all outdoor pools using cyanuric acid as a stabilizer maintain a minimum free chlorine residual of at least 2 parts per million (ppm).

Williams, Kent. Aquatic Facility Operator Manual, 3 edition. National Recreation and Park rd Society 1999


Cyanuric over 50 ppm As the level of cyanuric acid rises, free chlorine’s ability to act as a

disinfectant is weakened. At above 50 ppm of cyanuric acid, the time it takes to kill bacteria

in the water is longer compared to swimming pool water without

cyanuric acid. Also, as the level of cyanuric acid builds up, the chlorine will become

increasingly less effective in keeping the water clean and problems such as increased cloudiness

and exceeding combined chlorine limits can occur.- Shields, JM; Arrowwood, MJ; Hill, VR and Beach, MJ. (2007

“Inactivation of Cyrptosporidium parvum under chlorinated recreational waterconditions. Journal of Water and Health. In press.


High pH and CYA

Consider a pH of 7.8 that only has the effectiveness of 33% and cya at 50 ppm

FC 1 ppm = .0235 ppmFC 2 ppm = .05 pm FC 3 ppm = .72


CYA’s Effect on Bacteria Kill Time

Extremely high levels of CYA remain unstudied, but it’s clear that even at a level of 100 ppm, the bacteria kill time can be twice as long as in a pool with 50 ppm of cyanuric acid.

© 2008, Pool & Spa News May Issue


Alkalinity and CYA

Because cyanuric acid interferes in the measurement of Alkalinity, both Langelier and Ryzner Index use a correction factor of 1/3 reduction so a cya of 100 would reduce the Alkalinity by 33 imagine an Alkalinity of 90 is now less than 60 and is considered aggressive causing etching, pitting, staining of pool walls grout and plumbing.

Technical Bulletin 12-4 Pulsar Systems


THINGS YOU WILL NEED

• Chemical test kit LaMotte Color Q 7 is best or Taylor Test kit

• Pool skimmer nets A fine net and a deep leaf net• Vinyl Pool brush, Mixed Bristle Brush• Pool vacuum Hose and head• O-ring Lube• Chemicals – Chlorine (liquid or Cal-Hypo), Trichlor

Tabs, Acid, Sodium Bicarb and DE if filter is DE


Cleaning Order1. Step 1 - Test your pool water to determine the levels of chemicals present. If Acid is required add it

now. 2. Step 2 - Empty the skimmer baskets located at each end of the pool of any debris that has collected 3. Step 3 -Skim the pool with a net to pick up any leaves, bugs or debris floating on the water's surface,

and any toys or large sticks on bottom of pool. 4. Step 4 - Brush the swimming pool with the brush. ( Mixed Bristle preferred stainless and nylon) Start

at the shallow end of the pool, and brush the walls from top to bottom. Then brush the dirt and debris on the bottom down to the deep end, towards the main drain. Weekly top 12” and steps, Monthly all walls making sure to get around light and return nozzles.

5. Step 5 - Check your pool's pump basket, and clean weekly. Be sure to Turn off your system and turn the skimmers and main drain to "Closed." Remove the basket and clean out debris check lid O ring for lube. Replace the basket and turn the main drain valve back to "Open." Turn your system back on, and then open the skimmer valves. Make sure the pump is primed.

6. Step 6 - Vacuum your pool as needed but at least 1 time a month. Most of the time simply brushing your pool and running the filter will do the trick. Some pools even have cleaners that run along the bottom of the pool, catching any debris that sits. Follow your pool's instruction manual for vacuuming instructions if necessary.

7. Step 7 - Add appropriate chemicals. Follow the recommendations from the test kit you used in Step 1. 8. Step 8 – Check you pool level make sure the level is in the middle of the skimmer or bottom of wall

drain. Best to start this after step 1 but not before. If this step is done before checking chemicals you must wait 2 hours before testing water

9. STEP 9 – Final skim with fine net for any debris that may have been floating or fallen while cleaning.


Electricity

Electricity- Don’t run single speed pump systems during peek electricity usage times

1 pm till 7 pm electricity cost moreVS Pumps save money on electricity and extend

the life of equipment and can keep the water healthier.


TIPS

1) In Fall and Spring debris likes to stick to wall brush top 6 inches before skimming 2) Always retest water after adding water in the Summer it is good to start with adding water if needed two

hours before testing. 3) DE and Sand Filters need water to be back washed when pressure reaches 8 -10 pounds over starting

pressure/ If pressure is above 45 turn OFF System and inspect. Cartridge filter need washed when 10 psi over starting pressure. Watch for pressure dropping, this could mean problems in the filter.

4) 4. During the Summer or swimming season use Calcium Hypochlorite to shock the pool in, during the off season or winter months use 10% sodium hypochlorite (liquid shock) and stop the use of Trichlor tabs.

5) Remember to turn the water off and check the source water chemistry every 4 months, many times this will help you balance your pool instead of adding chemicals.

6) Filter cleaning a. A cartridge every 3 – 4 months is best but minimum 2 times a year. b. A DE every 6 months minimum 1 time a year. c. A Sand probe with dow rod yearly change sand every 4 years

texas pool schol salt pools evaporation_alk_ ph_chlorine_ cya effects

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