no chlorine

Chlorinating, maintaining the right chlorine levels,
chlorine problems. Dichlor, trichlor, cal hypo, bleach,
granules, chlorine pucks and chlorine sticks.
nagrath

no chlorine

Postby nagrath » Mon 17 May, 2010 08:20

Richard-
I have an electric cover, too, and was very pleased with how the pool was working my first year, and most of the second, with very little chemical usage. Last year we had the tabs run out while we were away, came back to a cloudy white pool and have had issues ever since. We also used a phosphate remover last year, which helped with the cloudiness problem, but I expect that's when we first got the ammonia. I will check out the pool school site and may try your method, as I do have 5 gallons of 12% chlorine at the moment!
Thanks again!
John


nagrath

no chlorine

Postby nagrath » Wed 19 May, 2010 19:00

Richard,
Just got my TF-100 kit and ran ALL the tests:
FC 1.5 on both tests, CC 2, TC 3.5, pH 6.8, T/A 160, CH 230, CYA ~30
So I STILL need to up my pH more, despite adding quite a bit of pH up already; TA is a bit high, though; glad I didn't add the additional alkalinity increaser the pool store recommended. Do I need to do another shock to get rid of the rest of the CC? How much chlorine would take care of that based on a 23,000 gal pool? I will go over the whole Pool School section as per your recommendation. Any hints you have would be great.

Thanks again,
John
chem geek
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no chlorine

Postby chem geek » Wed 19 May, 2010 20:57

Don't use pH Up to raise the pH since it will also raise your TA too much. You can either aerate the water (if the pH isn't really that much lower than 6.8 ) or you can use 20 Mule Team Borax to raise the pH with about half the rise in TA. Your high TA will result, in the long run, in the pH tending to rise over time. By the way, adjust your pH before you raise the FC too much since a high FC above 10 ppm will make the pH test read falsely too high (unless the pH is very low -- i.e. it makes 7.5 look like 8.0, but doesn't make 6.8 look much higher).

As for getting rid of CC, any oxidizer will do that. You don't need to buy an expensive non-chlorine shock. You can just use chlorinating liquid or bleach. I suggest opening up the cover and letting sunlight hit the pool at least part of the time. That combined with shock levels of chlorine (say, 12 ppm FC given your 30 ppm CYA) should clear the CC faster since sunlight helps break down some of the CC directly and also forms some free radicals from the chlorine that are more reactive than chlorine itself.
nagrath

no chlorine

Postby nagrath » Thu 20 May, 2010 05:25

Thanks, just what I was wondering--Pool School mentions sunlight, and borax. I'll get some . I still have liquid shock left over so will use that. Sounds like I'm almost there!

John
jackie

No chlorine

Postby jackie » Tue 29 Jun, 2010 12:18

PattyB wrote:I also have no Chlorine registering in my pool. Above ground pool, 28 foot round, 20,000 gallons. The hardness is 400 - which shows accurate per my test kit, The PH is at 7.2, The alkinity is 180 - slightly high, the stabliizer is 0. The water is slightly cloudy, it is clearing up. In the past week I have added 7 gallons of liquid chlorine to the pool along with two floats that are always in the pool filled with chlorine tablets. Can someone tell me how do I get the chlorine to register on the test strips? I have tried 2 different packages of strips and nothing is showing. Thanks!

I am having the exact problem. I have researched and treated my pool for phosphates... BUT still I have no chlorine reading. I've been told it is a "Chlorine Lock" and it must be treated by adding 5x the amount of usual chlorine. Have you had any other responses. I would appreciate hearing from you. I also have a 28' round w/ 22,000 gallons since we have a 6' hopper in the middle.
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no chlorine

Postby chem geek » Tue 29 Jun, 2010 13:38

There is no such thing as "chlorine lock". There are real things that happen in pools that are well understood, but not taught by the industry so most pool stores aren't aware of these issues.

First is that the amount of active chlorine (hypochorous acid) that kills pathogens, prevents algae growth, and oxidizes bather waste is proportional to the FC/CYA ratio. The continued use of stabilized chlorine products increases the CYA level over time so if you don't proportionately raise your FC target, the active chlorine level drops over time to the point where algae can grow faster than chlorine can kill it. At first, this may appear to just be a higher-than-normal chlorine demand, but at some point the water can turn dull then cloudy and eventually become a full-fledged algae bloom. The following are chemical rules of fact that are independent of concentration of product or of pool size:

For every 10 ppm Free Chlorine added by Trichlor, it also increases Cyanuric Acid (CYA) by 6 ppm.
For every 10 ppm FC added by Dichlor, it also increases CYA by 9 ppm.
For every 10 ppm FC added by Cal-Hypo, it also increases Calcium Hardness (CH) by at least 7 ppm.

So even with a very low 1 ppm FC per day chlorine usage, continued use of Trichlor pucks/tabs will have the CYA increase by over 100 ppm in 6 months if there is no water dilution. One can avoid these problems by using chlorinating liquid or bleach as the primary source of chlorine, but this needs to be added every day or two unless a mostly opaque pool cover is used in which case it can be added around twice a week. See the Pool School for more info.

The second thing that happens in some pools is that if the FC level gets to zero for an extended period of time (at least 8 hours), then bacteria can convert the CYA into ammonia and this can take a LOT of chlorine to get rid of. This usually happens when people close their pools too soon or open them too late and they "let go" their pools over the winter. When they open in spring, the CYA level has dropped significantly (even to zero) and the pool will not register any FC even after adding large amounts of chlorine. To prevent this problem, one should close the pool as late as possible when the water is cold (no higher than 50ºF and preferably colder) and should open as early as possible in the spring before the water warms up (no higher than 50ºF and preferably colder). One can also shock the pool with chlorine when they close and/or use PolyQuat 60 algaecide.
Roxanne

no chlorine

Postby Roxanne » Fri 24 Jun, 2011 11:14

Hi,
I have read through all 10 pages of postings on this topic. For the first time in 10 years I am also having problems with a zero chlorine reading in my above ground 24' pool. I live in Ohio and due to early bad weather, I had to close the pool last year dirty. When we opened it in the beginning of May, all the solids settled to the bottom and for the most part the water was a clear brown. I drained 3/4 of the water out and refilled it (well water that has lots of iron in it). The pool turned a bright dark green color...looks liked slimy swamp water. I ran the pump continuously, washed the filter 3 x a day and went through 25 lbs of shock, 3 bottles of algecide and 2.5 bottles of clarifier and finally the water is clear and has a sparkle to it. I also went through HTH 3 in 1 sanitizer skimmer tablets (a whole 25 lb bucket). Now I have switched to the regular HTH 3" sanitizer tabs because I thought something must be wrong with the first tabs due to not getting any chlorine reading. After reading all these postings, I am a little confused about what my next step should be. Since my pool was so filthy, I just figured all the chlorine was being used to kill all the algae. It appears that problem is pretty much under control, but now when I shock, I only get a chlorine reading for a couple hours after I shock and then it drops to zero. I have only been using test strips and the ph and the alkalinity are both just a tad high. According to the postings here I am confused...is there such a thing as chlorine lock or not? Do I super chlorinate again even though the water is clear? Did all that filth and slime turn the water to acid or ammonia? Plus, we have had so much rain lately, could that be causing problems too and when it's not raining, it has been very hot and sunny, so I initially thought the sun was burning off the chlorine, but the new tabs are stabilized so I'm not sure what to do now. I sure would appreciate if anyone could offer some simple advice (non chemist), for what I can try next. Thanks a bunch! :?
chem geek
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no chlorine

Postby chem geek » Fri 24 Jun, 2011 13:32

Yes, it is possible that bacteria grew when the chlorine level was zero and it converted some or all of the Cyanuric Acid (CYA) in the pool into ammonia (and partially decomposed CYA) creating a huge chlorine demand. You can see a log of my personal experience with this in this post . You can do a bucket test if you want using 2 gallons of pool water and adding 6% bleach to it until the FC level holds consistently. Every 1/4 teaspoon of 6% bleach in 2 gallons is 10 ppm FC. You really should have a better test kit, either the Taylor K-2006 or the TFTestkits TF-100 .

It is also possible that your CYA level is very high so the chlorine you add isn't enough to kill off algae that is still growing. Again, you really need a proper test kit to know what is really going on. The solution is different for the two. With ammonia, you keep adding chlorine until you get a reading. With high CYA and algae growth, you really need to get the CYA lowered with dilution and then hit hard with a high shock level as shown in the Chlorine / CYA Chart .

If your pool is small and either you need a lot of chlorine to get rid of the ammonia or your CYA is sky high, then you may be better off with a drain/refill (or at least multiple partial ones or a significant continuous drain from one end at the bottom and refill from the other end at the top).
Roxanne

no chlorine

Postby Roxanne » Sat 25 Jun, 2011 11:16

Thank you for your response. I am going to take a sample of my water to the pool store to have it tested and then will follow your advice from there. We have had a continuous rain for the past week and I noticed this morning that there is bright green algae starting to grow again in certain spots on the bottom of the pool...I need to do something quickly before it takes over again! Thank you for your help.
chem geek
Pool Industry Leader
Pool Industry Leader
Posts: 2382
Joined: Thu 21 Jun, 2007 21:27
Location: San Rafael, California

no chlorine

Postby chem geek » Mon 27 Jun, 2011 21:32

Many pool stores are notorious at doing the testing incorrectly. I strongly suggest you get your own good test kit and do the testing yourself. In the meantime, you could just keep adding chlorinating liquid or 6% unscented bleach to the pool until it starts to get an FC reading. Note that a high chlorine level above 10 ppm can bleach out a DPD chlorine test which is why the recommended test kits I listed use a FAS-DPD test that is not only accurate but won't bleach out (a flash of pink just has you add more powder to get a color).

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