no chlorine

Chlorinating, maintaining the right chlorine levels,
chlorine problems. Dichlor, trichlor, cal hypo, bleach,
granules, chlorine pucks and chlorine sticks.
wolf718
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same problem 2 yrs in a row

Postby wolf718 » Sun 25 May, 2008 10:25

For the second year in a row I am having a difficult (and expensive) time in getting the chlorine to hold after opening. I have a 16 x 32 (20,000 gallon)inground in northern Indiana. My Pentair filter is five years old and had the sand replaced with Zeobest last year. I had a new winter cover and we have had a very cool spring so far but the water has been green and cloudy since opening.
Here are the readings from first sample:
TDS: 1200
CYA: 50
Total Chlorine: 1.6
Free Chlorine: 1.6
pH: 8
Total Alkalinity: 210
Adj. Total Alkalinity: 195
Based on this they had me add 10lbs. of Super Soluble and 1 pt. of SwimTrine Plus. I also added four gallons of liquid chlorine I had left over from last year.
The next morning my Chlorine level was over 6 but they said that wasn't high enough based on what I added and that it wouldn't hold if I didn't hit it again.
So last night I added 12 lbs. of the 24 lbs. of BurnOut35 they sold me. This morning I am getting a chlorine reading of zero! It's Sunday morning and they will be closed for the next two days due to the holiday. I need to now what to do. I hate to add the other 12 lbs. of BurnOut35 if it is not working. If I need to drain, I would like to get started as soon as possible but I would really like to avoid this.
Any recommendations?


chem geek
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Postby chem geek » Sun 25 May, 2008 14:38

Did your CYA level drop over the winter and did you "let your pool go" over the winter without maintaining the FC level in it? If so, then soil bacteria may have converted some of the CYA to ammonia. You can get an inexpensive ammonia test kit from a pet/fish/aquarium store. If you have ammonia, then it takes a cumulative amount of FC that is 10x higher than the ammonia amount to break it.
Guest

Postby Guest » Sun 25 May, 2008 18:03

OK, according to the test strip there is ammonia in the water. I would say the amount is in the 1.5 to 2.0 ppm range. Which leads me back to one of my original questions, should I put in the additional 12 lbs. of BurnOut35? If not, what should be my next step?

By the way, thank you for the response. I plan on discussing the issue of maintaining/adding FC while the pool is closed with my pool supplier. They have never recommended I do that :x
chem geek
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Postby chem geek » Mon 26 May, 2008 00:09

It doesn't matter what source of chlorine you use (except that some sources add extra stuff -- Trichlor and Dichlor add Cyanuric Acid while Cal-Hypo adds to Calcium Hardness). BurnOut 35 is Lithium Hypochlorite which is the most expensive source of chlorine. You could just as easily use chlorinating liquid or unscented bleach, both of which are sodium hypochlorite. You can use The Pool Calculator to calculate dosages.

So, you would need to add around 20 ppm of chlorine to get rid of the ammonia (and the Combined Chlorine you earlier measured). Then, the chlorine should hold after that.

Richard
wolf718
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Joined: Sun 25 May, 2008 09:49

Postby wolf718 » Tue 27 May, 2008 20:46

Richard,

Last night I added 7 gallons of unscented bleach and 6 lbs. of BurnOut35.

Tonight, I tested for ammonia and got a zero reading. Unfortunately, I also get a zero reading for chlorine.

If I got rid of the ammonia why is the chlorine not holding? Would lowering the water level some (enough to keep circulation) then adding more bleach be worth trying?
chem geek
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Postby chem geek » Wed 28 May, 2008 06:43

See if you've got Combined Chlorine (CC). If so, then the chlorine has combined with the ammonia, but it will take more chlorine to get rid of this combined chlorine (which is monochloramine). It will take a few hours and exposure to sunlight will help.

I also assume your readings, such as CYA, are correct. Also, I assume you aren't using a DPD test (measuring intensity of pink/red color) since that will bleach out above 10 ppm FC having you think you have no chlorine when you actually have a lot.

If your chlorine holds overnight but disappears during the day, then you probably don't have the CYA level you think you have and the chlorine is breaking down in sunlight. Add the chlorine at night and measure it the next morning to see if this is the case.

Richard
Pool Person

Postby Pool Person » Thu 29 May, 2008 22:30

Hi to answer almost all of your problems what you should do is go to your local pool store and have them check for nitrates. Nitrates come from bird droppings, leaves, dirt, dust, and more importantly fertilizers.. even if you fertilize your garden 20 feet away, the fumes from the fertilizers can travel into the pool. This is what you do: for example say you have a 15,000 gallon pool. I would say you use about 2 bags or 2lbs to shock it. In order to kill these nitrates and "break this lock" you multiply your two bags of shock by 10. So then that equals 20 bags or 20lbs. Now the bags of shock can be expensive so if your local pool store carries big 5 gallon liquid drums of chlorine use that. Now 1 five gallon drum equals up to 7 bags. So you take the total numbers of bags that you would have to use and divide it by 7. So for the 15,000 gallon pool you would take the 20 and divide it by seven and you get 2.8. I would round that up to 3. That means you use 3 of those five gallon liquids of chlorine. The thing is you have to do it all at one time. You can't get one drum of chlorine and pour it in and then the next day do the other two. In order to break a chlorine lock and get rid of the nitrates is to hit it hard alll at one time. If you have any other questions post them!!
chem geek
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Postby chem geek » Fri 30 May, 2008 02:12

The pool store can also check for phosphates, but unless nitrates and phosphates are VERY high, then that won't explain the chlorine consumption. Nitrates and phosphates don't consume chlorine, but they are algae food so the growth of algae uses up the chlorine making it more difficult to combat with chlorine alone. However, at least for phosphates, one can use chlorine alone to control algae up to at least a phosphate level of 3000 ppb. I don't know the nitrates level where it is not worth using chlorine to control algae -- never had any pool on any pool forum with nitrates high enough to have that sort of problem.
Pool Person

Postby Pool Person » Fri 30 May, 2008 19:07

Well I tell all my customers to heavy shock it as i said before with the 10 times the amount and it breaks the lock and lowers and almost kills the nitrates and phosphates in the water.
chem geek
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Postby chem geek » Sat 31 May, 2008 12:12

Chlorine will not get rid of nitrates of phosphates. It will only kill algae that grows and uses nitrates and phosphates as food for such growth. The algae can come back and if it does with high nitrates and phosphates then it will grow quickly again. So if the phosphates are really, really high (say, 3000 ppb or higher), then a phosphate remover is useful. But normally, neither phosphates nor nitrates are that high and shocking with chlorine just gets rid of an existing algae bloom. If one then maintains an appropriate Free Chlorine (FC) level relative to the Cyanuric Acid (CYA) level, then algae growth can be prevented with chlorine alone. For manually dosed pools, the minimum FC is 7.5% of the CYA level (this rule works up to a phosphate level of around 3000 ppb).

The most common reason for algae in pools is an FC level that is too low relative to the CYA level. The FC/CYA ratio roughly determines the amount of disinfecting chlorine (hypochorous acid) that does the actual killing of bacteria and algae.

The 10x rule for chlorine is most relevant when dealing with ammonia (measured as ppm Nitrogen). The industry also refers to the 10x rule for getting rid of Combined Chlorine (CC) though technically it doesn't take that much chlorine.

Richard

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