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SWIMMING POOLS
CHLORINE
Effectiveness Of Chlorine On Viruses (3/9/99)
Differences Between Chlorines (3/9/99)
Chlorine Tablets / Vinyl Pools (3/9/99)
Chlorine & Effect On pH (9/2/98)
Feeders And Chlorine Levels (9/2/98)
Liquid vs. Tablet Chlorine (8/19/98)
Are Trichlor Tabs & Sticks Interchangeable? (8/3/98)
Trichlor Tablets / Raising Chlorine Level (8/3/98)
Granular Chlorines / Residue (7/9/98)
Chlorine Neutralizer (6/1/98)
Proper Chlorine Levels With Ozonator (5/28/98)
Deteriorated Chlorine Tablets? (5/28/98)
High Chlorine Levels In Pool (5/26/98)
Converting From Baquacil To Chlorine (4/28/98)
Assorted Swimming Pool Chemistry Questions (4/27/98)
Effectiveness Of Chlorine On Viruses (3/9/99)
Q:
I am very curious if chlorine used in pools is powerful enough to kill viruses. It is a fact that certain viruses are present in feces and it is also a fact that very young children have "accidents" in pools.
L.W. - Bairnsdale, Australia
A:
Chlorine is pretty much an equal opportunity killer. Chlorine will destroy organic matter, including viruses, upon contact.
The speed and effectiveness depends upon several factors including: concentration of free chlorine, pH, time in contact, circulation, temperature and quantity of organic matter present.
It's used to treat water all over the world because it is effective!!!
I hope that I have been helpful.
Sincerely,
Alan
Differences Between Chlorines (3/9/99)
Q:
Could you please tell me the difference between Sodium Hypochlorite and Calcium Hypochlorite? Is one just the liquid form of bleach??
D.B.
A:
Sodium and calcium hypochlorite contain different chemicals and concentrations, but once added to the water form the same active ingredient: Chlorine in the form of Hypochlorous acid.
Liquid bleach contains chlorine at 3.0-5.25%. The liquid product used in pools is 10-15% active. The calcium hypochlorite product contains approximately 65% chlorine -- you don't have all the water to carry around.
I hope that I have been helpful.
Sincerely,
Alan
Chlorine Tablets / Vinyl Pools (3/9/99)
Q:
Can I use chlorine tablets on vinyl pools? I was told that it burns the vinyl.
F.S. - Poway, CA
A:
Millions of people are using trichlor tablets in the their vinyl pools, without a problem. THE ONE THING YOU CANNOT DO IS TO PLACE THE CHLORINE TABLET DIRECTLY ON THE VINYL. TO DO SO WILL BLEACH OUT THE COLOR. Chlorine tablets should be used in a floater or a feeder.
I hope that I have been helpful.
Sincerely,
Alan
Chlorine & Effect On pH (9/2/98)
Q:
Our ph is 7.8; 7.6 is suggested as ideal. Will shocking or the addition of chlorine on start-up lower the ph at all?
M.S. - Tulsa, OK
A:
A definite maybe!!!
The optimum range for pH is 7.2-7.6. The various products for shocking or chlorinating have pH value ranging from low to high. It depends on which product or products you are using.
The following products have a high pH: Calcium or Lithium Hypochlorite and Liquid Chlorine.
The following products have a low pH: Trichlor and most non-chlorine shock for pool use.
The following is essentially neutral: Dichlor.
I hope this helps.
Sincerely,
Alan
Feeders And Chlorine Levels (9/2/98)
Q:
We are having a problem maintaining the proper level of chlorine. Do you know a way to test the feeder to see if it's really working?
H.P. - Somers, CT
A:
Make sure that the feeder is kept reasonably full of tablets. Do not wait for all the tablets to dissolve. Make sure that the system is operated for enough hours daily.
If the feeder is not providing sufficient Free Chlorine it may be because the bather load is high or that there is algae present. If the feeder is set at maximum and there is a shortage of chlorine, it may be necessary to supplement the feeder with periodic shock treatments. After heavy rainfalls, periods of high bather load or at the first signs of algae, shocking the pool is a good idea. The feeders, in current use, are not capable to providing quick boosts in the chlorine level. Shock, on the other hand, is quick dissolving, and able to provide a quick boost in chlorine levels.
I hope that this information will prove helpful.
Sincerely,
Alan
Liquid vs. Tablet Chlorine (8/19/98)
Q:
We changed pool maintenance companies recently and I can't seen to get a common consensus from anyone regarding the use of liquid vs tablet chlorine. The new pool man wants to use chlorine tablets instead of the liquid chlorinators we currently use for our large pool and spa. He said it's better than liquid because it takes longer to dissolve and there is less salt than in the liquid format. The last pool maintenance man was a staunch believer in using liquid. The local pool supply shop said liquid was better because it withstood sunny days better. I've tried to get an answer from the health department to no avail. What is your recommendation?
D.H. - Garden Grove, CA
A:
When you add liquid chlorine to the pool water, there is an immediate increase in the chlorine level. The level reaches an immediate peak and continues to drop until more product is added. The chlorine level is a series of peaks and valleys.
The trichlor tablets are slow dissolving. When used in a feeder they slowly dissolve and release chlorine on a continuous basis. This avoids the peaks and valleys and makes for a more comfortable chlorine level by avoiding high levels.
Occasionally trichlor tablets cannot keep up with the demands of the pool because of bather demand, heavy rains or signs of algae. Under these conditions supplementing the trichlor with liquid chlorine would be a good idea.
I hope that I have shed some light on the subject.
Sincerely,
Alan
Are Trichlor Tabs & Sticks Interchangeable? (8/3/98)
Q:
Our family has just purchased a 24 ft. round 52" high above ground pool. The question I would like to know is: what is the difference between a 3" tablet and a stick. We have an automatic chlorinator. Our local pool store has a once-a-week program that uses the sticks. Can I use 3" tablets, which are cheaper?
M.G. - Sussex, NJ
A:
The sticks and the 3" tablets should both contain the same material. Read the labels.
If the chlorinator being used with the sticks does not preclude the use of the tablets I see no reason against making the substitution. You can substitute a quick-dissolving chlorine or non-chlorine shock for the shock product.
I hope that I have been of assistance.
Sincerely,
Alan
Trichlor Tablets / Raising Chlorine Level (8/3/98)
Q:
We have an inground pool 17' x 35' and 10' deep. I can't get the chlorine level to come up. I have been adding enough tablets for a pool with 35,000 gallons of water in it. The pool is not green but it is cloudy. The ph tested okay. Help before the season ends.
R.K. - Niagara Falls, NY
A:
Trichlor tablets are slow dissolving and are not designed to play catch up. You need to shock the pool.
Add sufficient shock to raise the FREE CHLORINE level to a point that gives you a reading of at least 3 PPM the next morning. At that point the tablets should be able to maintain a proper level.
You should shock at first signs of visible algae, after heavy rains or after periods of heavy bather use.
Try adding SUN Algalator. It will help clear up the cloudy water.
Hope I've been of assistance.
Sincerely,
Alan
Granular Chlorines / Residue (7/9/98)
Q:
I have been using strictly granular chlorine this year. The pool is sparkling clear and no signs of any green. My question is: Do the granulars completely dissolve? When I add it I walk around the pool and sprinkle it in.
Last night I vacuumed the pool on direct waste and removed everything. Then I added about a 1.5 lb of granular. This morning the bottom has residue on it. I am not sure if it is the chlorine or a problem with the filter. Can I add the granular directly through the skimmer?
I also used your suggestion adding the D.E. for better filtration and I thought maybe the residue on the bottom was the D.E. bypassing the sand. That is why I did a direct waste vacuum.
P.M.
A:
Granular chlorines such as dichlor or lithium hypochlorite do not contain residues. Calcium hypochlorite does contain some insolubles. If you are using cal Hypo, you are not following the directions - read the label.
Adding chlorine through the skimmer is not my preferred method.
If you are using dichlor or lithium, it is possible the D.E. has passed through the filter. This could be a sign of channeling. When was the sand changed last?
I hope this information proves helpful.
Sincerely,
Alan
Chlorine Neutralizer (6/1/98)
Q:
After shocking the pool, I use sodium thiosulfate to reduce the level of chlorine the following day. Is any amount of sodium thiosulfate added to the water ever unsafe? I mean, is there a risk of "over neutralizing" as far as swimmers are concerned. Also, what risk does too much chlorine pose for swimmers?
J.G. - Jermyn, PA
A:
Adding too much chlorine neutralizer, will remove all the chlorine and eliminate its sanitizing effect. NOT GOOD!!!!
Chlorine neutralizer should be added in cases of extreme overchlorination only.
Too much chlorine can be irritating to the skin and eyes and cause "bleaching" of bathing suits.
Make sure that you are testing for FREE CHLORINE - that is the active form of chlorine. The good stuff!!!!
I hope that I have been helpful.
Sincerely,
Alan
Proper Chlorine Levels With Ozonator (5/28/98)
Q:
I have an ozonator and automatic chlorine supplier on my pool. What level of free chlorine should the supplier be maintaining?
S.P. - Great Falls, VA
A:
The ozonator should allow you to get by with a lower level of free chlorine. 0.5 - 1.5 PPM should do the trick.
Make sure that all other pool water parameters are maintained, as if the pool is solely on chlorine.
I hope that I have been of assistance.
Sincerely,
Alan
Deteriorated Chlorine Tablets? (5/28/98)
Q:
My father in law recently dismantled his pool and gave me a container of HTH pellets. Since I have been using them my pool has become cloudy. I have had the water tested and added the recommended product along with liquid chlorine. I went one step further, I mixed a large quantity of these hth pellets in a pail of pool water, stirred and then tested with a test strip, only to find that the strip indicated no chlorine whatsoever. Does hth chlorine have a self life? I can not tell you how long my father in law had this container, but I would suspect spring of 1997 or earlier.
R.H. - Windsor, Ontario Canada
A:
If the chlorine was stored properly, there is no reason to suspect that it was deteriorated.
It is possible that the solution you tested with the strip was so strong that it bleached out the color.
The cloudy water could be due to lack of chlorine, inadequate filtration, excessive calcium hardness, lack of water balancing or all of the previous reasons.
I suggest that you bring a sample of water into a local pool professional for a complete water analysis. This should give insight as to the cause or causes.
I hope that I have been of assistance.
Sincerely,
Alan
High Chlorine Levels In Pool (5/26/98)
Q:
I just opened my pool (18 X 33 above ground) this year. I took a sample of the water to my local pool place . I needed to raise the alkalinity and the hardness of the pool. The person at the pool place commented that the Chlorine level in the pool was 3 ppm and asked if I had already shocked the pool. I told her I hadn't yet. She suggested that I not shock the pool. When I was done adding the chemicals to raise the hardness and the alkalinity, I left the filter (DE) running. After about 3 hours, I noticed the water had started to turn a very slight green color. The next day the pool was a much darker green. I checked the Chlorine level in the pool again and it still was approximately 3 ppm (I had not yet put a chlorine tablet in the skimmer basket yet). Based on the color of the pool, I decided to shock the pool and did so with 2 lbs of powdered shock. By the next morning, the pool was crystal clear. However the chlorine level is still 10 ppm. The previous season, whenever I shocked the pool, the chlorine level would remain high for as much as 5 days.
What I would like to know is what could be causing the chlorine to remain in the pool. The pool gets about 6 hours of direct sunlight each day and is not covered with a solar cover. Any information or suggestions you might have would be helpful.
R.S. - Wells, ME
A:
If you are using an OTO Chlorine Test, as I suspect, you should switch to a test kit that measures FREE CHLORINE. Free Chlorine is the active form of chlorine and is a better measurement of the pool's sanitizing ability. OTO measure total chlorine.
Typically, free chlorine values are lower that total chlorine readings. The difference between the two reading is combined chlorine, which is irritating and odorous.
Try using Sun Non-Chlorine Shock. It can drop the combined chlorine, while raising the free chlorine.
I hope that I have been of assistance.
Sincerely,
Alan
Converting From Baquacil To Chlorine (4/28/98)
Q:
I have used Baquacil for four years. Last year my pool was only clear for a couple weeks. This year I am changing over to chlorine. Should I drain the pool or try converting the old water? It is a mess, cloudy and has pink algae. My husband wants to drain but I feel we can clear it up with chlorine. What do you think?
B.B. - East Liverpool, OH
A:
To convert from Baquacil it is not necessary to drain your pool.
To convert from Baquacil add 4 gallons of liquid chlorine or 4 pounds of Sun-Brite Shock for each 10,000 gallons of water. Run filter and test for Free Chlorine after a few hours. Adjust pH to 7.2-7.6. Pool will probably turn brown-green due to the decomposition of the Baquacil. Retest for FREE CHLORINE and, if not present, add additional shock until a free chlorine level is being maintained. Once a free chlorine level is being maintained, continue with regular chlorine maintenance program. Addition of SUN Tru-Blue will help clear up the water.
Good luck and I hope that I have been of assistance.
Sincerely,
Alan
Assorted Swimming Pool Chemistry Questions (4/27/98)
Q:
I was wondering, what is the best way to measure chlorine levels? What are the common pollutants which occur in backyard swimming pools and what is the best way to get rid of them? Also, is it true that chlorine can be lost from pools in sunlight? Is there any way to prevent this from occurring? Also, I am worried about the pH in my swimming pool. What happens if the pH is too low/too high?
Nicole - Mackay, Australia
A:
The best way to measure chlorine is with a test kit that measures FREE CHLORINE.
Common pollutants include: bather waste, body oils, cosmetic residues, micro-organisms, algae and wind blown debris. Chlorine and/or shock treatment is most effective way of dealing with these materials.
UV light can destroy chlorine. Using a chlorine stabilizer will help minimize loss due to the sun's UV light.
Low pH can cause corrosion, irritation and can cause chlorine to become too aggressive. High pH can cause cloudy water, scaling, irritation and a decrease in the sanitizing ability of chlorine.
I hope this information is helpful.
Sincerely,
Alan |
