Balancing Your Pool With Target Ranges by Bob Lowry
Why is balancing your pool so important? The main reason I think and one overlooked at times is that the water can look great and inviting but it could actually be a breeding ground for pathogens that can make a swimmer very ill. Bob Lowry is the foremost expert on swimming pool chemistry and he answers these questions and more in the podcast series I recorded with him.
Bob Lowry teaches Target Chemistry and here are his recommended target numbers. Not a range but a specific number to shoot for.
Sanitizer 3.0 ppm
After the alkalinity & pH are brought into range, the next adjustment is the sanitizer. Liquid Chlorine or Bleach is the most common and least expensive of the available sanitizers. The acceptable range is 1.5 - 3 ppm, though 4 - 5 ppm is absolutely fine. A commercial spa should be maintained at much higher levels - 5 - 6 ppm. Bob Lowry has the Target at 3.0 ppm so you should always aim for that for your residential pool.
A residential pool should be maintained at 3.0 ppm. The higher levels ( 4 - 5 ppm) should be established, prior to a large party or heat spell. Try not to allow the levels to drop below 3 ppm, as this will prevent the need to shock or take other corrective action after the party.
ALKALINITY 90 ppm
There are a number of factors that contribute to the "balance of the water." The most important is the pH and the alkalinity. The alkalinity is the ability of the water to buffer the pH (or buffer chemicals that may affect the pH). The alkalinity is like an auto-pilot or cruise-control for the pH.
If the alkalinity is out of the acceptable range, then any small factor will cause a wild swing in the pH. This is called "pH bounce." Because of this, the alkalinity is the first thing that should be brought into line when balancing the water.
An ideal range for the alkalinity is 100-120 ppm (though 80 - 140 ppm is acceptable).
pH 7.5
The pH of the water determines if it is acidic or basic. Either extreme can have disastrous effects on the pool finish, equipment, or plumbing. When the pH is out of range, bathers may complain of eye discomfort or other ailments.
An acidic pH will cause the water to become aggressive. It will etch the plaster and cement finishes around the pool. Worse yet, it will dissolve the metallic components of the pool. The most expensive metallic component is the copper heat exchanger within the pool heater.
The ideal range for the pH is 7.4 - 7.6 (though 7.2 - 7.8 is acceptable).
HIGH OR LOW TOTAL ALKALINITY:
Total Alkalinity will determine the speed and ease of PH change.
If the starting PH is 7.6 in a 15,000-gallon pool and the Alkalinity is 120 ppm, if you add 1 pint of Muriatic Acid it will drop the PH to 7.0 and the Alkalinity to 105.
If the starting PH is 7.6 in a 15,000-gallon pool and the Alkalinity is 60 ppm, if you add 1 pint of Acid it will drop the PH to 6.7 and the Alkalinity to 26ppm.
So you see it is very important to keep the Alkalinity in the good range of 80-120 ppm. Alkalinity basically determines the waters ability to neutralize the acid.
Low alkalinity will cause:
Etched Plaster
Corroded Metals
Stained plaster
PH to creep, drift lower
Eye & skin irritation
High total Alkalinity will cause:
Scale formation
Cloudy water
Difficulty changing PH or the PH will drift up
Eye & skin irritation
So to adjust high alkalinity down you want to use Muriatic acid or Dry acid. When doing this it is important to test the acid demand before starting to lower the total Alkalinity. Never add more than ½ gallon of acid and don't add acid more than 3 times in one day.
If the total Alkalinity is high in a matter of hours the PH will rise. This happens because high total alkalinity will neutralize the acid. High alkalinity will create a constant high acid demand.
RAISING Total Alkalinity:
use SODIUM BICARB (Alkalinity Up {Baking Soda]) when you want to raise Alkalinity without raising the PH. Soda Ash will raise both at the same time. 20 oz of Alkalinity Up will raise your Alkalinity by 10 ppm (10,000 gallons).
One final note, the type of Sanitizer you use will determine your total Alkalinity level.
If you are using Trichlor 3" tablets, gas chlorine or bromine, the alkalinity should be kept in a higher range as each time these are added it will lower total alkalinity.
A neutral sanitizer like Dichlor (granular chlorine), will not raise or lower total alkalinity so you should try and keep it at 100 ppm.
High PH sanitizers like liquid Chlorine and Cal-hypo (shock) will raise your PH and total alkalinity so you should keep it in the low range 80-100 ppm.
Cyanuric Acid (Conditioner) 50 ppm
You add this to your pool water to protect the chlorine from being burned off rapidly from the Sun's UV rays. without Cyanuric acid (CYA) in your pool water, the chlorine will only last a matter of hours. With the proper level, the chlorine can last 5-10 times longer.
The ideal range is 30-50 ppm although it is okay if it is 80-100 ppm. Any higher and the chlorine starts to become less effective and you will need larger amounts of sanitizer in the water to maintain the chlorine level.
Note that Tri-chlor tablets and Dichlor will both add significant amounts of CYA to your pool water. Limit the use of these or your CYA can rise above 150 ppm or higher in one season.
Calcium Hardness 350 ppm
This is mainly determined by your water source. If your fill water is hard then the pools calcium hardness will be high. The Ideal range varies with surface type but 200-400 ppm is acceptable.
If your Hardness is low:
Water balancing will be difficult
Etching of plaster
Corrosion of pool equipment
Eye & Skin irritation
Foaming
To raise the calcium hardness add calcium chloride
High Hardness:
Scale formation on pool and equipment
Cloudy water
Eye & skin irritation
Water balancing will be difficult
To lower calcium hardness you will need to drain all or some of the water and refill the pool.
Podcast recordings:
“Why
is Balancing Your Pool Important Anyway?” With Chemistry Expert Bob Lowry:
https://www.buzzsprout.com/110832/6680642
“Is
High CYA Really a Problem?” With Chemistry Expert Bob Lowry:
https://www.buzzsprout.com/110832/6681473
“Is
Cyanuric Acid Testing Accurate?” With Chemistry Expert Bob Lowry:
https://www.buzzsprout.com/110832/6682265
“Preventing
Algae in Your Pool” With Chemistry Expert Bob Lowry:
https://www.buzzsprout.com/110832/6683519
“Swimming
Pool Metal Staining 101” With Chemistry Expert Bob Lowry:
https://www.buzzsprout.com/110832/6683558
“Borates,
Are They for Real?” With Chemistry Expert Bob Lowry:
About Bob Lowry:
Robert W. Lowry
The Pool Chemistry Training Institute (PCTI) provides books and courses for residential pool service technicians. We have the experience and the credentials that we impart to all of our trainees for pool chemistry certification.
Bob Lowry was a technology officer for DEL Ozone an ozone generator manufacturer. He has been a consultant to numerous corporations including DuPont, Olin, Nalco, Arch, and FMC and to pool industry companies such as Natural Chemistry, LaMotte, ITS, Pentair, and Jacuzzi
Mr. Lowry has written 21 pool and spa water chemistry books published more than 175 technical articles, written 29 “white” papers, written a monthly column for Pool & Spa News, given more than 500 water chemistry seminars, and has certified more than 2,500 students to be CPOs (Certified Pool Operators). He wrote the 3 IPSSA training manuals which have more than 425 pages on water chemistry.
In addition, he has formulated, invented, developed, and introduced more than 111 new chemical products into the pool and spa industry. His last invention was instant conditioner (quick-dissolving liquid chlorine stabilizer – sometimes called liquid CYA).
In 2017 he revised, updated, and re-published the IPSSA Basic Training Manual and the IPSSA Intermediate Training Manual. Also in 2017, he translated the IPSSA Basic Training Manual into Spanish.
Swimming Pool Service and Maintenance Guide Books
In 2018 he published two additional books. Pool Chemistry for Service Pros which is a 28-page how-to book and a 226-page resource book called Pool Chemistry for Residential Pools.
Pool Chemistry Publications
PCC Logo Patch 072218
Also in 2018, he co-founded Pool Chemistry Training Institute which offers a 1-Day Residential Pool Chemistry Certification course called Pool Chemistry Certified – Residential or PCC-R aimed primarily at service technicians but can benefit retail stores and even pool owners. It is the only pool chemistry certification course in the industry.
Pool Water Chemical Calculator Apps
He has developed Pool Water Chemistry Smartphone Apps – a pH calculator for calculating acid doses and how to lower pH in pools, a pool calculator for calculating chemical doses, a pool calculator for calculating the Saturation Index, and a pool gallon calculator for calculating pool water drain amount.
Visit my Website: http://www.swimmingpoollearning.com/
YouTube Video Index: http://poolmandave.blogspot.com/2014/03/swimming-pool-tips-reviews-how-to-video.html – A list of all of my videos.
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