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 » Tue 11 May, 2010 15:42

OK, bucket test says 1 tsp chlorine bleach (I believe mine is 5.25% strength) brings me to a FC of 10ppm (or more, that's the highest on my strip); what does that translate too? I am getting confused with all the various strengths and units.

john


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no chlorine

Postby chem geek » Tue 11 May, 2010 23:53

If 1 teaspoon of bleach in 2 gallons got you to over 10 ppm, then that's good and means that it will take no more than 40 ppm -- probably less than 30 ppm -- of cumulative FC before chlorine starts to hold in your pool. So you can just start out adding 10 ppm FC to the pool and see if it holds. If it doesn't, add more. I think you're really close at this point. Probably somewhere between 20-30 ppm FC needs to be added to your pool before the chlorine starts to hold.

You should seriously consider getting a better test kit so you can test higher chlorine levels. The best test kits are either the Taylor K-2006 you can get at a good online price here or the TF-100 kit from tftestkits.net here which has more volume of reagents so is comparably priced per test.
Nagrath

no chlorine

Postby Nagrath » Wed 12 May, 2010 04:56

Richard,
Thanks. Because I am worried about not adding enough to deal with the ammonia I want to make sure I add enough at once; if I only do 10ppm at first (about (about 5.5 lb cal-hypo 48%, which is what I have), how long can/should I wait before testing and adding more? And is it OK to use cal-hypo instead of liquid bleach? How can I calculate the projected increase in hardness if I do, or should I just wait and add the CH afterwards once I retest and have enough FC? I will order a good test kit; I had hoped I would be able to pick one up locally, but was not able to.

John
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Postby chem geek » Wed 12 May, 2010 12:39

John,

Yes, you can use Cal-Hypo instead of bleach if you want to. For every 10 ppm FC added by Cal-Hypo, it will also increase Calcium Hardness (CH) by at least 7 ppm. So unless your CH is high already, the use of Cal-Hypo should be OK.

You can add 20 ppm FC if you want -- I just didn't want you to overshoot too much, but it's not a horrible problem if you do since you've got some CYA in the water already.

Since you've got CYA in the water, I'd wait at least an hour after adding the chlorine before testing. If you find that it is high in Combined Chlorine (CC) but still has a lot of Free Chlorine (FC), then wait another hour. If the FC gets low, below 10 ppm, add more chlorine to bring it back up.

Richard
nagrath

no chlorine

Postby nagrath » Wed 12 May, 2010 12:58

Richard,
Thanks, My wife found an excellent deal on liquid shock, so I was able to get that; I will let you know how it goes. If I am successful, should my total chlorine and free chlorine be roughly equal, and the ammonia be close to zero? If not, do I need to add more? I have about 12 gallons of 12% liquid shock available to work with now; hopefully that will do it!

Many thanks,
John
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Postby chem geek » Thu 13 May, 2010 20:28

You'll know you are done when the Free Chlorine (FC) level holds and doesn't drop more than 1 ppm overnight (i.e. when the sun is not on the pool) and that you have <= 0.5 ppm Combined Chlorine (CC) which is the same thing as saying that the Total Chlorine (TC) is not more than 0.5 ppm than the FC. You really should get yourself a good test kit -- either the Taylor K-2006 you can get at a good online price here or the TF-100 from tftestkits.net . Or if you already have all the other tests including pH, TA, CH and CYA, then you can just get the FAS-DPD chlorine test .

When you are done, the pool will also be crystal clear and the ammonia reading will be zero in addition to the FC holding and CC <= 0.5 ppm noted above.
nagrath

no chlorine

Postby nagrath » Sun 16 May, 2010 12:17

Richard,
Ammonia gone, Chlorine was up to 5ppm yesterday (I used 7 gal 12% chlorine), but has now gone down to about .5; chlorinator is now on with trichlor tabs, pool is clear, all other levels look good, at least as well as I can test them; ordered a test kit, too. Total chlorine is less than .5 over free chlorine, so I *think* we did it. Hopefully the chlorine will stabilize soon. Thanks for all your help!
John
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Postby chem geek » Sun 16 May, 2010 13:38

That's good news. Note, however, that using Trichlor pucks/tabs will raise the CYA level over time unless your pool has significant water dilution. For every 10 ppm Free Chlorine (FC) added by Trichlor, it also increases Cyanuric Acid (CYA) by 6 ppm. So even with a low 1 ppm FC per day chlorine usage, this would be over 100 ppm CYA in 6 months if there is no water dilution.

If the FC level is not raised proportionately with the CYA level to keep the FC/CYA ratio constant, then algae can grow faster than chlorine can kill it. In a manually dosed pool, the FC should be at least 7.5% of the CYA level. Even in an SWG pool, it should be at least 4.5% of the CYA level. When the FC drops below this level, algae can grow faster than chlorine can kill it while above that level algae doesn't grow, even with all of the nutrients (phosphates and nitrates) it could possibly need. The reason is that algae growth is also limited by sunlight and temperature.

If you plan on continuing to use Trichlor and ignoring this FC/CYA issue, then you will need to use a supplemental algaecide, such as PolyQuat 60 weekly, or a phosphate remover (both are extra cost, of course) to take the edge off of algae growth. It won't completely stop it, but can buy you more time so that the CYA can get higher without having to raise the FC as much.
nagrath

no chlorine

Postby nagrath » Sun 16 May, 2010 19:13

Richard,
Duly noted! No one had ever told me about this issue. Is there something else I could use in my chlorinator? Doesn't the CYA get degraded in any way over time? If what you say is true, it seems like a self-defeating way to maintain a pool! It will be interesting to monitor the CYA accurately; last year I NEVER registered ANY level of CYA in the pool on my aquatest strips. I orderet the TFT test kit today; that should allow me to track everything accurately. Obviously, I have to make damned sure I never get to a point where my FC goes to zero as happened last year.

Thanks so much for your help.
John
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no chlorine

Postby chem geek » Mon 17 May, 2010 00:05

I suggest you read the Pool School to learn more. Trichlor tabs/pucks are convenient because they slowly dissolve, but they come at a price of increasing CYA levels unless your pool has significant water dilution. I maintain my 16,000 gallon pool shown here and here using 12.5% chlorinating liquid I add twice a week (I have a mostly opaque electric safety cover so around 1 ppm FC per day chlorine usage with the pool used 1-2 hours every day) plus a small amount of acid every month or two. That's it -- it costs around $15 per month in chemicals. No algaecide, no phosphate removers (in spite of having 2000-3000 ppb until recently diluted), no clarifiers, no flocculants, no weekly shocking, no metal ions, etc.

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