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Thread: Just filled spa, low chlorine levels, what to do?

  1. Back To Top    #1

    Join Date
    Oct 2015
    Location
    Kelowna BC
    Posts
    47

    Just filled spa, low chlorine levels, what to do?

    Hi all! First of all this is my first time on here, and thanks in advance for any help you can give me!

    A couple days ago I just filled our 1500L hot tub for the first time. We just bought our house in the beginning of the year and the hot tub was currently running and maintained by a spa service. Then we had it drained as we were not living in our house and weren't going to use it till this fall.

    So I cleaned out debris, filled it up and added a cleaner solution to it, put the pumps on high for an hour and then drained it and rinsed it and drained it again. Then I filled it up again. I tested the fresh water with the following results:

    FCL 0
    TCL 0
    Alk 180
    pH 7.5
    TH 100

    Then I filled the chlorine floating dispenser with fresh pucks/tablets and unscrewed the top to open the vents to about the "3" mark on the stem as recommended by the local spa store. Next day I did another test:

    FCL 0
    TCL .5
    Alk 180
    pH 7.5
    TH 100

    So the chlorine levels were very low even though the dispenser was floating around. So after doing some research I found that one must also do an initial shock to fresh water on the first fill. So I did that, then tested right away:

    FCL 10
    TCL 5-10
    Alk 180
    pH 7.5
    TH 100

    So that was much better, obviously too high to swim in right away. But the instructions on the ZAP Oxydizer said one could swim in it in 20 min. A couple hours later I decided to increase the hardness by adding a hardener substance. This seemed to nicely put the hardness at around 250, tested right before we went in to the tub last night and I thought the following numbers were great:

    FCL 3
    TCL 3
    Alk 180
    pH 7.5
    TH 250

    Last night I took the floating dispenser out while we were in the water as I heard one must do, but not sure about that, then put it back in after we left.

    Today however, chlorine levels are way back done to nearly nothing like they were when I initially had the floater in

    FCL 0
    TCL .5
    Alk 180
    pH 7.5
    TH 250

    So I have cranked open the vents on the chlorine floating dispenser to "8" instead of 3, hoping this will dissolve more chlorine into the water. I'm not sure what these numbers mean, and tried to Google it extensively without much help, I first thought they were referring to the ppm of chlorine desired. The numbers go up to about 12 I think.

    Any suggestions? Will the 8 level work on the floater? Thanks!!

  2. Back To Top    #2
    Texas Splash's Avatar
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    Jun 2014
    Location
    South-Central Texas, Marion/San Antonio
    Posts
    12,934

    Re: Just filled spa, low chlorine levels, what to do?

    Hello and welcome to TFP! Not to worry, there are many people here who will gladly try to answer your questions. First question though - how are you testing your water? That is very important. Hopefully it's with a Taylor K-2006 since in BC I don't think you can get the TF-100. But it all starts there. The one very important item missing from the test readings above is your CYA. We must know the CYA in order to determine how much FC (free chlorine) goes in the water. One thing for sure though, having no FC is never a good thing and means there is no chlorine to sanitize the water right now. Also, in the future you can simply list hardness as "CH".

    Besides confirming how you got those test results, please add your pool info to your signature by going to the top of the TFP web page (just under the Pool School button) and select "SETTINGS". On the next page look to the left for a menu bar that says, “MY SETTINGS” and go to "EDIT SIGNATURE" to enter your pool and equipment info there. It will help us later. Once we hear back from you, it should give us better info to assist. Welcome to TFP!
    Pat (a.k.a. Texas Splash) ~ My Pool: Viking Fiberglass; 17,888 Gal; Waterway Supreme 2-sp/2-hp pump; Hayward Ctg filter; TF-100 w/ Speed Stir
    Vital Links: POOL SCHOOL, RECOMMENDED LEVELS, RECOMMENDED CHEMICALS, Poolmath Calculator, SLAM, Chlorine/CYA CHART.
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  3. Back To Top    #3

    Join Date
    Oct 2015
    Location
    Kelowna BC
    Posts
    47

    Re: Just filled spa, low chlorine levels, what to do?

    Quote Originally Posted by Texas Splash View Post
    Hello and welcome to TFP! Not to worry, there are many people here who will gladly try to answer your questions. First question though - how are you testing your water? That is very important. Hopefully it's with a Taylor K-2006 since in BC I don't think you can get the TF-100. But it all starts there. The one very important item missing from the test readings above is your CYA. We must know the CYA in order to determine how much FC (free chlorine) goes in the water. One thing for sure though, having no FC is never a good thing and means there is no chlorine to sanitize the water right now. Also, in the future you can simply list hardness as "CH".

    Besides confirming how you got those test results, please add your pool info to your signature by going to the top of the TFP web page (just under the Pool School button) and select "SETTINGS". On the next page look to the left for a menu bar that says, “MY SETTINGS” and go to "EDIT SIGNATURE" to enter your pool and equipment info there. It will help us later. Once we hear back from you, it should give us better info to assist. Welcome to TFP!
    I thought I replied but I didn't see it show up here and wasn't sure if posts are still having to be approved yet? Anyways, thanks for the welcome and I've modified my signature.

    It's a LaMotte Insta-Test 5 test strips and I use NutraFin pH test kit as the strips don't give an easy read on the pH for me. Also it seems that the FCl is now somewhere between .5 and 1. This is when I opened the vents on the floater to "8"I was also wondering how the CYA works, dosn't FCl give an indication of how much is being added or how much exists in the water?
    Sundance Calypso Hot tub 1500 L, 2 pumps, Taylor K-2006 test kit

  4. Back To Top    #4

    Join Date
    Jul 2015
    Location
    South County, Rhode Island
    Posts
    28

    Re: Just filled spa, low chlorine levels, what to do?

    Hi Dave, Welcome. In my personal opinion, your spa is not clean. That is why the chlorine is being eaten up. My two cents would be to get some Ahh-Some spa cleaner and follow the directions to the letter. Drag a shop vac over to have on hand when you are doing this, it is very handy for vacuuming up the dirty foam.

    Do it as many times as necessary until you are satisfied that the spa is clean. I have actually heard of people doing it 8,10,12 times in a row. Yes, spas can be that disgusting sometimes. I am not an expert, I just have seen the results of Ahh-Some and it is a great product. I used it on my brand new spa and got slime out of it. Best to you. PS. An accurate test kit is a must as Pat mentioned.
    2015 Bullfrog 131 180 gal Spa Indoor, TFP bromine fed, Taylor K-2106
    2012 2500 gal. Round vinyl AG Pool, Hayward Easy Clear Filter System, chlorine
    1994 Rubbermaid 175 gal horse tub, still looking for advice on algae problem.

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