no chlorine

[delmonteken]

Hi Richard
I am over in Spain and I am interested in the fact that you are not getting a reading as it would appear that I am not either. What I would like to know is when you do the test for chlorine what colour does your water go when you put the drops in your test kit. The reason me asking is my water does not go the yellowish colour to get a reading , mine goes like and orangy colour this is what I can describe the colour as. And its driving me crazy. I have shocked my pool done a test and nothing still the same orangy colour. So if you can help in any way or anyone else who reads this I would greatly appreciate anyones help on the matter

Richard,
It seems that I am still struggling with this problem; I opened up the pool this spring; it was slightly greenish and slightly cloudy; used a Trichlor shock product twice, and the pool cleared up pretty quickly (3-4 days); however, once again I am getting no free chlorine. Pool store tested (using a photometric reader, though I don't know the test they use (it IS a drop test, though), and I came up with ph 7.2, total alk 100, cya 0, free chlorine 0, phosphates 0. How is it I am getting a CYA of zero if I shocked with trichlor and have been using 3" trichlor tabs in my chlorinator? Can the chlorine bleach out the CYA test? I will get the ammonia test; I should have done that last year but did not. Do I correctly understand that I can use regular liquid bleach (if it is unscented) to shock (especially in this case, if I need to add a tremendous amount)? I am nearly at my wits end; the pool looks beautiful, but I get no chlorine reading, even though I smell chlorine when I open the pool. Ugh!

Thank you for all your help; I wish I had followed through on everything last year.

Sincerely,
John

[chem geek]

John,

Just so I understand, you got through this problem last year and finally got the pool to read Free Chlorine (FC) OK, but now you've opened up the pool again this year and have a similar problem, correct? If you let the chlorine level get to zero over the winter, then bacteria could certainly have converted some or all of the CYA into ammonia or at least started to break it down. That can create a huge chlorine demand. You can prevent this by either maintaining some chlorine in the pool over the winter or at least closing when the water is cool (50ºF or below) with a shock level of chlorine and then open the pool in the spring before the water warms up (still 50ºF or below).

So you can get an ammonia test kit to see how much ammonia there is in the pool. You can also do a bucket test to determine the chlorine demand where 1/4 teaspoon of 6% bleach in 2 gallons of pool water is 10 ppm. Add the bleach, stir, test after 10-15 minutes, see if you get an FC reading. If the FC is low, add more chlorine and repeat until you get a consistent FC reading of at least 10 ppm. This will give you a rough idea of how much chlorine you need to add to the pool -- it could be a lot.

You can use chlorinating liquid from a pool store or hardware / big-box store if they carry it or you can use Clorox Regular 6% unscented (or off-brand Ultra unscented) bleach for the pool.

Richard

[chem geek]

Hi Richard
I am over in Spain and I am interested in the fact that you are not getting a reading as it would appear that I am not either. What I would like to know is when you do the test for chlorine what colour does your water go when you put the drops in your test kit. The reason me asking is my water does not go the yellowish colour to get a reading , mine goes like and orangy colour this is what I can describe the colour as. And its driving me crazy. I have shocked my pool done a test and nothing still the same orangy colour. So if you can help in any way or anyone else who reads this I would greatly appreciate anyones help on the matter

It sounds like you are using an OTO test kit. This will not bleach out at high chlorine levels and instead will go from yellow to orange to even red or brown when the chlorine level gets very high. So it sounds like you have a lot of chlorine in your pool -- probably in the 10-20 ppm FC range.

So your chlorine level is probably too high, but you have a lousy test kit. Since you are in Spain, see if you can get both a PalinTest SP 315C (Balanced Water and Chlorine/pH/Cyanuric Acid) and also SP 300 (FAS-DPD chlorine test). The 315C tests for FC, TC, pH, TA, CH, CYA while the 300 is a better chlorine test for FC and CC that won't bleach out and can accurately measure shock levels of chlorine. You really need a test that can check your CYA and other levels.

Is your pool vinyl lined or is it plaster or fiberglass? You mentioned in an E-mail that your pool walls are becoming discolored like a dary grayish going blackish in color in the grout lines -- is this a tile pool? I've never heard of high chlorine levels turning plaster walls gray.

[nagrath]

Richard,
Thanks! I have my work cut out for me and will do just what you say tomorrow. Pool was shocked and closed when cool, and opened when cool, but I JUST BARELy got the chlorine level up in the fall when I was last having the problem, and maybe I was fooling myself. I will get to work on this tomorrow; Thanks a million!

John

[nagrath]

Richard,
Got the test kit for ammonia--4 ppm. Had water retested at another pool store with very modern equipment. Total chlorine 2.7, free chlorine 0, CYA 30, alk 60 (that just dropped from ~100 at last test) Hardness 83, pH 6.6; they suggest 12-14 bags of shock/bottles of liquid shock. I have not done the bucket test yet. Their granular shock is Calcium hypochlorite; I bought some, as the price was good and it was convenient; is this OK to use to super-hyper-chlorinate and break the combined chlorine, as we discussed doing with liquid chlorine? Also, I was told to balance the pH and alkalinity and hardness before chlorinating. However, I am thinking the calcium ions in the calcium hypochlorite will add to the hardness, no? Should I use less of the hardness product? I could not get a good liquid test kit, but got LaMotte test strips which appear to be more accurate and do test hardness and total chlorine as well as free, and match the store's testing pretty well. Any words of wisdom and experience?

[nagrath]

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

[chem geek]

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]

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

[chem geek]

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]

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

[chem geek]

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]

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

[chem geek]

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]

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

[chem geek]

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.