Become a TFP Supporter Pool Math Forum Rules Pool School
Results 1 to 8 of 8

Thread: Testing for free and combined chlorine?

  1. Back To Top    #1

    Join Date
    May 2010
    Location
    Mountain View, Arkansas
    Posts
    64

    Testing for free and combined chlorine?

    I am learning the ropes of keeping up basic pool maintenance at my home. I have a 30,000 gallon pool. I took my pool water to the local pool place which is an hour away and the results were as follows:

    Free Cl = 9.5
    Total Cl = did not measure (she wasn't sure why it didn't register)
    Temp = 70
    Saturation Index = 0.1
    CYA = 50
    pH = 7.8
    Tot Alk = 104
    Adj Total Alk = 89
    Manganese = none
    Total Hardness = 221

    I use Hth products and use 3 in TriClor Tabs. I use 2 tabs in one skimmer every week and shock every 7 to 10 days with 5 lbs of Cal Hypo. I use clarifier and an algae preventive once a week too. I also just run the filter 24/7 and backwash approx once a week for about 2 minutes and then rinse for 30 seconds. My question is am I doing this right and how do I measure for Total and Free Chlorine? I know if I can measure both of them I will be able to get my Combined Chlorine reading. I am using an Aqua Chem 6 way test kit and it seems to measure everything fairly good except chlorine. I do the test from this kit and it seems to read between the 3.0 and 5.0 level. Any help and suggestions would be greatly appreciated.

    Thanks,

    Al
    Mountain View, Arkansas, 23,000 gallon in-ground concrete pool with a 24-in Hayward Pro-Series Sand Filter with side-mount. Chlorinator is attached but only use occasionally and a 1 hp pump.

  2. Back To Top    #2

    Join Date
    May 2010
    Location
    Mountain View, Arkansas
    Posts
    64

    Re: Testing for free and combined chlorine?

    I live in Mountain View, Arkansas and pool is concrete with plaster siding I think. Filter is a hayward, not sure of size but says it flows at 75 g.p.m. I will get all this info and get it on my signature. I'm not to computer savvy. Sorry and hope this helps
    Mountain View, Arkansas, 23,000 gallon in-ground concrete pool with a 24-in Hayward Pro-Series Sand Filter with side-mount. Chlorinator is attached but only use occasionally and a 1 hp pump.

  3. Back To Top    #3
    frustratedpoolmom's Avatar
    Join Date
    May 2007
    Location
    SWSuburban Chicago, IL
    Posts
    11,963

    Re: Testing for free and combined chlorine?

    Have you read Pool School? That's a great place to start and a lot of information there - many of your questions can be answered with the articles there.

    If you want my honest opinion, you sound like a typical pool owner but you could really save yourself alot of money and effort if you utilize the BBB methods.

    FYI, you should stop using the HTH tablets because they contain copper, which you do not want in your pool.

    A properly chlorinated pool rarely, if ever needs shocking, especially not every 7-10 days.

    A combined chlorine higher than .5 is a bad thing. Sounds like she didn't test correctly, you want it to be 0 but the TC should be SOMETHING.

    I would recommend a better test kit - there is an article in Pool School.

    Backwashing is indicated by a 6-10 psi increase - not necessarily weekly. If your gauge doesn't indicate the filter is dirty then it isn't necessary to backwash (though sometimes the gauge is not accurate, but the return flow decreasing is a sign you should backwash.

    In any event, you can SAVE a TON of money by following the BBB method - once you understand WHAT you are putting into your pool and why; once you understand you don't need several of the products you are using - you won't have to purchase them any more.

    Post back after reading Pool School if you still have any questions.
    Helpful links: Pool School; CYA/Chlorine Chart
    24' round AG pool, 52" high, Raypak heater; Waterway 2 spd Pump;
    150 Sq ft. Clearwater Cartridge Filter; Former and DISSATISFIED "Pool Frog" owner
    http://www.PerfectlyClearPoolService.com

  4. Back To Top    #4
    Guest

    Re: Testing for free and combined chlorine?

    75 GPM filter and 3 HP pump? You might want to double check that!

    Welcome to the 'page!!

  5. Back To Top    #5

    Join Date
    May 2010
    Location
    Mountain View, Arkansas
    Posts
    64

    Re: Testing for free and combined chlorine?

    The pool school information is awesome! And I will be looking into the BBB methods. I'm all about saving a buck and it looks much safer and simpler. And as far as my pool filter I'll have to double check the 75 GPM and 3 HP. I am using older ones and all the info has been scratched. I open to all suggestions from everyone and this site is definitely the best I've seen.
    Mountain View, Arkansas, 23,000 gallon in-ground concrete pool with a 24-in Hayward Pro-Series Sand Filter with side-mount. Chlorinator is attached but only use occasionally and a 1 hp pump.

  6. Back To Top    #6

    Join Date
    May 2010
    Location
    Mountain View, Arkansas
    Posts
    64

    Re: Testing for free and combined chlorine?

    I decided I am giving the BBB method a try. I was using the 3-inch Tri-Chlor tabs which seem to be a very good pool chlorinate, but I don't see the advantages to using them if it's going to put a lot of copper and raise CYA-levels quickly in a 6 to 7 month pool season. I will be using the standard 6% off brand bleach that I can get for $2.37 for 1.42 gallons at Wallyworld. Since this has about 94% other ingredients, does anyone know what they are and do they put bad stuff in your pool? Also, since this is an un-stabilized chlorinate I know it dissipates much faster, so will I have to add chlorine everyday to maintain a total/free chlorine level of around 3 to 4? Just curious how often others have had to add chlorine and if I should be adding something everyday.

    I also have been reading through a lot of the pool school and other post on here and I can't believe the great information that I have found. And I'm all ears forany other pointers on the BBB method. Looks like I plan on saving some money and will be a lifetime contributor to this site very soon.

    Thanks for all the pool lessons so far.

    Al.
    Mountain View, Arkansas, 23,000 gallon in-ground concrete pool with a 24-in Hayward Pro-Series Sand Filter with side-mount. Chlorinator is attached but only use occasionally and a 1 hp pump.

  7. Back To Top    #7

    Join Date
    Mar 2007
    Location
    San Rafael, CA USA
    Posts
    12,085

    Re: Testing for free and combined chlorine?

    Al,

    Trichlor tabs don't normally add copper, though some specific tabs might. All Trichlor tabs, however, increase the Cyanuric Acid (CYA) level where for every 10 ppm Free Chlorine (FC) that they add, they also increase CYA by 6 ppm.

    6% Bleach is, by weight, 6.0% sodium hypochlorite (i.e. chlorine), 4.7% salt, and 89.3% water. All sources of chlorine will add salt to the pool as chlorine turns into chloride (salt) when it gets used up, but bleach adds salt upon addition as well. Salt is rather innocuous except at very high levels so this extra added salt is not a problem. With bleach (or chlorinating liquid), for every 10 ppm FC you end up with 16 ppm salt. For Trichlor, you end up with half the salt, 8 ppm, but as noted above you also get 6 ppm CYA which is much more of a problem at lower levels.

    It is not true that unstabilized chlorine dissipates faster. All chlorine added to water is IDENTICAL when dissolved. The only differences in chlorine products are in what else they add to the water and how much they change the pH. If you already have CYA in the water, then adding bleach vs. Trichlor produces IDENTICAL chlorine that lasts the same amount of time regardless of source of chlorine. The reason you need to add chlorine every day (or two) with bleach is because it is not a slow-dissolving tablet -- it has nothing to do with it being unstabilized. If you had an automatic chlorine dosing system, then you wouldn't need to add the bleach manually -- Trichlor tabs are like an automatic dosing system because they dissolve slowly. Now it is true that if you were to add bleach to water that didn't already have CYA in it then sunlight would break down the bleach rather quickly (half lost every hour, roughly), but you know better than that and would put CYA in the water first.

    If you have a pool cover, then you might be able to add chlorine every 3 days or twice a week. It all depends on how much is lost to sunlight how quickly. A higher CYA level can protect the chlorine to last longer during the day, but the downside is that it's harder to fight any algae problems if the CYA is high. Usually for manually dosed pools, somewhere around 50 ppm CYA is a decent balance. No matter what your CYA level, you need to maintain the appropriate FC level for that CYA level as described in the Chlorine / CYA Chart in order to prevent algae growth.

    Richard
    16,000 gallon outdoor in-ground 16'x32' plaster pool; Pentair Intelliflo VF pump; Pentair IntelliTouch i9+3s control system; Jandy CL-340 square foot cartridge filter
    12 Fafco solar panels; Purex Triton PowerMax 250 natural gas heater (200,000 BTU/hr output); automatic electric pool safety cover; 4-wheel pressure-side "The Pool Cleaner"

  8. Back To Top    #8

    Join Date
    May 2010
    Location
    Mountain View, Arkansas
    Posts
    64

    Re: Testing for free and combined chlorine?

    Thanks Richard. My CYA is currently at 50 ppm. Looks like between 4 to 6 ppm is my FC goal. I keep a log book and see how much bleach I am using a week. But still seems it will be much cheaper than the alternative. This will be my first year of actually doing my pool maintenance myself and I have a lot of interest in learning what I can from you guys. Thanks again.
    Mountain View, Arkansas, 23,000 gallon in-ground concrete pool with a 24-in Hayward Pro-Series Sand Filter with side-mount. Chlorinator is attached but only use occasionally and a 1 hp pump.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •