Chlorine lock?

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Ok, I am learning here. So I need to forget about the general idea of the pool store telling me to keep my FC at 3. I see there is a direct relationship between target FC and CYA. The lower the CYA, the less your target FC, and thus the less bleach I need to add to hit the target. That being said, you cannot go too low on the CYA either. So is looks like the ideal CYA level is 30-50, which would put my target at 4 to 6ppm, which would put my bleach needs at 1.25gal to 1.75gal. Now the question I have, is in a perfect world, if everything was balanced, a pool is still going to lose FC, so do you guys test weekly, and add the bleach to hit the target, then forget about it until the end of that week, and repeat? Or??

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I have read all that and my last post indicates, I am getting a deeper understanding. I have learned so much in the last 2 hours from all you folks! I got my test kit from here - Taylor K-2006 Test Kit. Pool. Taylor K-2006.
 
Glad to hear you've done the reading. Each time you read it, things will sink in better.

Weekly additions don't work. Some people use a dosing system for liquid chlorine, or a saltwater chlorinator, but otherwise about the best you'll achieve is additions every 2nd day during the swimming season with sunny weather. To get to weekly maintenance, you need a very clean pool and a dosing system.

And yes, you got it. The pool store is flat-out wrong advising you to keep FC at 3 PPM if you have CYA at 80 PPM. It is extremely likely that the pool is not safe for swimming and will turn green.
 
Just chiming in with some thoughts. Dichlor will add CYA so, don't use it. I only use dichlor/trichlor pucks in the chlorinator when I can't be around for a few days. Once you get to know your pool's chlorine consumption, it is just a matter of adding bleach at regular intervals. Right now I've been testing FC every day to get a feel for chlorine loss in a day. My pool eats 3ppm FC each day. I can add a jug of 8% bleach every other day and barely need to test. Consumption and amounts vary due to pool size, equipment, bather load, sun exposure, CYA level, etc. But get to know it, and it's easy.
 
cholmes28 said:
Ok, I am learning here. So I need to forget about the general idea of the pool store telling me to keep my FC at 3. I see there is a direct relationship between target FC and CYA. The lower the CYA, the less your target FC, and thus the less bleach I need to add to hit the target. That being said, you cannot go too low on the CYA either. So is looks like the ideal CYA level is 30-50, which would put my target at 4 to 6ppm, which would put my bleach needs at 1.25gal to 1.75gal. Now the question I have, is in a perfect world, if everything was balanced, a pool is still going to lose FC, so do you guys test weekly, and add the bleach to hit the target, then forget about it until the end of that week, and repeat? Or??

- - - Updated - - -

I have read all that and my last post indicates, I am getting a deeper understanding. I have learned so much in the last 2 hours from all you folks! I got my test kit from here - Taylor K-2006 Test Kit. Pool. Taylor K-2006.
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The K-2006 is one of the recommended kits!!

Please understand that the "pool store" system of keeping the chlorine between 1- 3 and shock every week is a recipe for you to keep going into the store and buying "stuff". The science behind the chlorine/CYA relationship was first published in the 1970's. The pool industry just refuses to acknowledge the science.

I can tell you, you have something growing in the water. Your water may be clear, it may look nice but if you pour chlorine in and it disappears quickly then something is consuming it.

I hate to say it but you need to replace more water an get that CYA down to a more reasonable number. I lived in Kennesaw for five years so I know Cobb county water is not that expensive.

Once the CYA is at a reasonable number it is time to read the directions on SLAMing your pool in the How To section of Pool School and follow that procedure completely to the end.


  • CC is 0.5 or lower;

  • You pass an OCLT (ie overnight FC loss test shows a loss of 1.0 ppm or less);
  • The water is clear.

When all three are true, you are done SLAMing and can allow the FC to drift down to normal levels.

Jason has already given you your reading list, so take some time and read through the articles he linked.

If you keep going to the pool store they are going to keep "guessing" and selling you stuff you don't need.
 
needsajet said:
Take it to 9 ppm FC with bleach after the sun is off the pool. Test about 30 minutes to an hour later. That's your start number. Measure in the morning before the sun hits the pool.
Click to expand...

I should have mentioned the water should be circulated by the filter pump before the morning sample as well.
 
Ok, in spite of my CYA being around 80, I just started the OCLT. I added 312 oz of the 10% walmart liquid chlorinator. I will run pump for 30 min, then test to get my baseline. Then about 7 AM tomorrow (before sun hits water), I will test FC again and report results. Can I run the pump all night, so it will be mixed before my AM test, or do I have to get up 30 mins before test, and start pump? Or I guess I can change my timer setting. Would rather run pump all night, unless that is not good to do.
 
cholmes28 said:
Ok, in spite of my CYA being around 80, I just started the OCLT. I added 312 oz of the 10% walmart liquid chlorinator. I will run pump for 30 min, then test to get my baseline. Then about 7 AM tomorrow (before sun hits water), I will test FC again and report results. Can I run the pump all night, so it will be mixed before my AM test, or do I have to get up 30 mins before test, and start pump? Or I guess I can change my timer setting. Would rather run pump all night, unless that is not good to do.
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You can run it all night if you wish.
 
Ok, after 30 mins of running pump, I just tested to get a baseline for the OCLT, and there is only 1ppm FC (added 5 drops to turn color) and .4ppm CC. Did I not run pump long enough after adding the bleach or what? The amount of bleach I added (312oz of 10%) should have raised me from 0 to 9ppm!!!

Update - thinking I did not circulate water long enough before testing for my baseline, I waited 2 hours with pump on, and just retested. FC dropped from 1 to .8, and CC is still at .4

I will retest in AM, but I don't really think this OCLT is going to be valid with a starting base of only 1ppm. Why did I lose so much chlorine? Now what?
 

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OK, no need to muck around any longer. No OCLT needed. The chlorine is being consumed by whatever is growing in the pool, and we need to kill it.

You can drain/refill around 1/2 your water to lower your CYA. That's the best next step, and the most practical approach because it will take half as much chlorine to get the SLAM underway, and your chlorine consumption through the SLAM is likely to be lower as well.

If you don't want to do that, you can jump straight into the SLAM at 32 PPM FC. The initial charge is 1100 oz (8.6 gallons) or 9 by 121 oz jugs of the 10% chlorine you mentioned. You will also need more chlorine to maintain the SLAM than you would at a lower CYA, but possibly not double. I've done the numbers, but please do your own for your own peace of mind and to double-check mine. Best to do your own numbers always.

Before doing this, you'll need to review the instructions in Pool School - SLAM - Shock Level And Maintain and follow them as closely as possible to keep your SLAM as short as possible.

Let us know which way you want to go and ask any questions along the way.

Getting the pool clean, safe and well balanced will reduce your long term maintenance substantially, both in terms of time and dollars.

After the SLAM is complete and the algae has been killed off, your maintenance level for 80 PPM CYA will be bare minimum 6 PPM FC and a target of 9 PPM FC in order to prevent further problems. For 40 PPM CYA, as an example, it would be bare minimum 3 PPM FC and target of 5 PPM FC.

Either way, for normal pool operation, you'll be adding an average of around 90 oz of 10% chlorine per day, replacing a rough average of 2.5 PPM FC per day. This number will vary depending on bather load, weather, etc. Maintenance alternatives include a liquid chlorine dosing pump, a saltwater chlorinator or manual dosing. If you leave the CYA high, it will gradually come down now that you're not using dichlor, due to splashout, backwashing, and overflow from rain.

It really works and I know you'll be happy, so I'm looking forward to hearing which way you would like to go.
 
Thanks to all for the education. I am going to drain/fill until I get the CYA to around 50. Then I will start the SLAM. I assume that I need to keep people out of the pool, and dogs from drinking the water until all this is done??

One side question - I have never met a pool service guy who follows the TFP method, and when I used to pay them for weekly service, they always kept my pool free of problems, or when the algea came, they were always able to get rid of it pretty quickly using other chemicals like algaecide. Perhaps this question belongs somewhere else, but are they all wrong? I mean if I called my old pool guy today, I feel pretty certain that he would tell me to drain/fill to get CYA down but would then dump in the a ton of chlorine and algaecide and brush/vacuum to waste. and within a day or two, I would be swimming again.
 
The pool is safe for swimming when:
FC is between minimum and shock level for your CYA level (see FC/CYA Chart linked in my signature)
pH is 7.2 to 7.8
You can clearly see the bottom of the pool in the deepest place

Side question: TFPC is safer, more reliable and lower cost, and the pool should never turn green (especially the day before a party).
I wouldn't say they're all wrong, but rather that their objectives are different from the pool owner's objectives.

That's how I see it anyway.

I think drain/refill is a good decision and will be less work for you in the long run. If you're in an area with a high water table, consider doing multiple drain/refills. If you have experience with drain/refills with no problems on your pool, obviously that's way better knowledge than mine!
 
I just drained about 6k gal from pool, which is 22%. I am refilling now, and hopefully that will bering CYA to around 50-60. Then I need to make sure my pH is in the range. As far as the SLAM, I get that I need to look up the Shock FC for my CYA, and add that to the water, I would assume after sun is off pool?

What I don't understand is how often do I test, and do I keep adding the bleach every time I test to try and maintain the shock FC level? I mean, what if I add the first dose, and test 2 hours later, and it is 0 ppm, do then add another full dose? Or if the FC level dropped 50%, do I go back to the calculator and figure out how much to bring back to the shock level and add that? It would seem that in the beginning, someone who tests 6 times a day is going to be adding a lot more chlorine, than someone who tests 2 times a day. In other words, is the goal regardless of how often I test, to try and maintain the shock FC level, until there is less than 1ppm loss overnight? Further, if testing during the day, do I add the bleach right after each test, even though pool is in full sun, or is this a test, then add bleach at night thing until clear?
 
cholmes28 said:
I just drained about 6k gal from pool, which is 22%. I am refilling now, and hopefully that will bering CYA to around 50-60. Then I need to make sure my pH is in the range. As far as the SLAM, I get that I need to look up the Shock FC for my CYA, and add that to the water, I would assume after sun is off pool?

What I don't understand is how often do I test, and do I keep adding the bleach every time I test to try and maintain the shock FC level? I mean, what if I add the first dose, and test 2 hours later, and it is 0 ppm, do then add another full dose? Or if the FC level dropped 50%, do I go back to the calculator and figure out how much to bring back to the shock level and add that? It would seem that in the beginning, someone who tests 6 times a day is going to be adding a lot more chlorine, than someone who tests 2 times a day. In other words, is the goal regardless of how often I test, to try and maintain the shock FC level, until there is less than 1ppm loss overnight? Further, if testing during the day, do I add the bleach right after each test, even though pool is in full sun, or is this a test, then add bleach at night thing until clear?
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Nope, start the SLAM as soon as you get a good CYA reading and the pH has been adjusted to 7.2.

From what I have seen, the quickest SLAMs happen when the pool owner is motivated. That means for the first couple of days testing the water and adjusting the FC back to shock level often, even as often as hourly. Remember to brush the pool. Look around hte pool for "hidden areas" like inside light niches and around stairs. If there is any possibility of areas with poor circulation then stirr that area up well with your net or brush after adding the chlorine each time.
 
Amazing when things work. I am about 2" left on the refil, and CYA is down to about 60 or a bit below. I expect that it will be around 50 by the time I am done filling. pH is 7.2, TA is 70, and CH is 130. Finally, I can start SLAM. Gonna start with 6 gal of 10%. I will test again in a few hours. So every time I test, if FC is less than 22, then I need to add enough bleach to bring it back to 22, and keep doing that until I do not lose more than 1 ppm overnight?
 
Yes, I got the dpd to not ball up. I find that if I mix it up and only take the fine powder, it doesn't do that anymore. Plus I watched a Taylor video, and I was putting way too liitle in. Just picked up 32 gallons of 10% from wal mart. Starting SLAM now. Will report back.
 

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