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Thread: TFPC for Swim Spa

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    Join Date
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    Winnipeg, MB
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    TFPC for Swim Spa

    We've had our Arctic Ocean series 5,500L swim spa for almost a year. During this time, I've learned alot about water care for hot tubs, and enough to realize that using the TFPC method is how I want to maintain the water. We run our unit year round, live in Canada and during the winter months, we transform the spa into a hot tub maintaining a water temp of 102F. During the summer, we run it around 94F. We are not avid swimmers but enjoy the large body of water, and entertain family and friends regularly. The whole "how to properly" sanitize to make it safe for everyone is something I take seriously. Prior to the switch to TFPC we were using a Dichlor tab floater. Weekly maintenance consisted of topping up, checking TA, pH, adding good doses of MPS to oxidize waste. Once a month I swap dirty filters with clean ones. To clean the filters I soak them for 48 hrs in a 5 gallon pail with a mixture of 1/2C TSP and 1C Cascade dishwasher detergent, followed by 12 hr soak in chlorinated water. The water was inconsistent at best. It sometimes had "musty" smells and sometimes got cloudy. CYA was through the roof as was the TDS. I've read the BBB / TFPC method over and over, and we are now going to maintain our water this way. However, I am only three weeks in and have some questions.

    Here are the steps I have taken to date;

    1. Decontamination
    I super chlorinated to about 15ppm for 24 hrs. Following that I added 4 oz of Ahhh-some. I thought this process was going to be super gross, but it was not as bad as I thought. After about 3 hrs, all of the "gick" had come out of the spa. The "gick" was captured the Ahhh-some did its thing. I then drained over night. The next day I got inside and super-cleaned the entire shell, removed all the jets and cleaned them. Rinsed everything really well, disposed of old filters, replace with brand new and then begin the fill.

    2. Refill
    With two 5/8" garden hoses, the fill (5,500L) took 3 1/2 hours. While refilling, I had a dealer test the fill sample. They use the Lamotte Spin Test Lab. I was given these results,
    FC – 0.88
    CC – 0.23
    pH - 7.4
    TA - 72
    CH - 101
    CYA - 2
    I based my initial dosing amounts against the readings above. I use The Pool Calculator for all dosage amounts.
    The city's waterworks website showed these results.
    FC – 0.83
    CC – 0.21
    pH - 7.45
    TA - 66
    CH - 81
    CYA - n/a
    Interestingly, the fill water had a slight green tint to it. I'm not exactly sure why. I had pre-filters on each garden hose.

    3. Brought the Spa up to 80F
    The source water was 38F. It took 21 hours to get to 80F.

    4. Added / Adjust TA, CH, Borates and Dichlor as follows;
    1. Baking Soda (may not do that next time) as it drove pH up a bit from the fill, which was a perfect pH. Goal was to increase TA to 80ppm from 72ppm.
    2. Muriatic Acid 2 oz to bring pH down. Only got it down to 7.8-ish
    3. Waited 1 hr…tested again. pH was at 7.7 to 7.8
    4. Added Calcium to increase hardness in two doses. Waited 3 hrs between doses. I added enough to bring up to 150
    5. Waited 3 hrs after last Calcium dose
    6. Added Dichlor
    7. Waited 1 hr
    8. Added Borates in 4 doses one after the other
    § Targetted 38 on pool calculator
    · Each dose had 8 oz muriatic acid and 460g of 20 Mule Team Borax; therefore total of 32 oz MA and 1840g Borax



    Here’s where things are at today;
    The water looks and feels amazing, and is so fresh.
    OCLT is <2ppm FC
    Today I tested and used the same sample water for each test.
    Home Testing with Taylor K2006:
    FC – 2.5
    CC – <0.5 (I use the 0.5ppm 10 ml test)
    pH - 7.7 (Its hard to discern exactly, but for sure it is not in the 8.0 range. So I did an acid demand test. Two drops showed 7.5, therefore I deduce 7.7 as my result)
    TA - 70
    CH - 180
    CYA – 30 (calc’d based on the amount of Dichlor added to date…I’ve just recently switched to Clorox 8.25%)
    Borates – 38 (Est’d based on dosage)

    Dealer testing with Lamotte Spin Test Lab:
    FC – 1.64
    CC – 0.28
    pH – 8.1
    TA - 42
    CH - 171
    CYA - 29

    My questions….
    Whose numbers do I trust?
    There is a big difference between the pH and TA numbers.
    Should I be concerned with the CC numbers, noting that the original fill water had a non-zero value to start with. My .5ppm FC tests show the very, very slightest pink when adding R-003. One drop of R-0871 produces a clear result practically as it hits the test sample.

    My maintenance Chlorine amount to add daily (if no one has used the spa in a 24hr period) is 7 oz Clorox. Does this sound reasonable? My math is based on the starting pre-soak FC (target is 2ppm) and the 24 hr chlorine decay of 3.2 ppm.

    If we are to trust my Taylor numbers, is there anything I should be doing? I’m feeling like I should address pH, but have resisted pending feedback I receive from this post.

    If I were to have family over on the weekend, and there will be 6 people hanging out for upwards to an hour (total), my math tells me that I would add about 28.4 oz Clorox after the party is over. Would I not want to add some Clorox before the party so I don’t run out? How much and how do I calculate this and then calculate what to add post-soak taking into account what was added before. I’m not sure what to do here.

    Sorry for the long post, but thanks for reading. I look forward to your replies.
    Arctic Ocean Swim Spa - Acrylic and Fiberglass - 5,500 ltr (1,453 US gals)
    Taylor K-2006 and K-1004 test kits

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    Mod Squad tim5055's Avatar
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    Re: TFPC for Swim Spa

    Welcome to TFP!

    Always trust your numbers!

    You can bring the pH down a little with muratic acid. But, a little bit goes a long way in the small body of water you have.

    Always remember, it is safe to swim up to the shock/SLAM level of FC for your CYA leel. So, adding before folks show up is fine, just don't go overboard unless you know there are kids who don't understand the whole going in the pool issue or adults who may have a few too many..... FC/CYA Chart

    Now, you keep saying Clorox, but remember generic is fine. Got a Canadian Tire close by? The sell everything including 10% chlorine most of the time....
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    Re: TFPC for Swim Spa

    Thanks for the feedback!

    I will trust my Taylor test numbers. It just seems weird that the dealer test is so "off" on the pH and TA. Any thoughts on why this might be?

    For a party...given CYA 30, would a FC of 8-10 ppm seem reasonable as a starting point? If so, guidelines I've read for FC of between 3-5ppm seems to go out the window. Thanks for helping me understand.
    Arctic Ocean Swim Spa - Acrylic and Fiberglass - 5,500 ltr (1,453 US gals)
    Taylor K-2006 and K-1004 test kits

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    Mod Squad tim5055's Avatar
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    Re: TFPC for Swim Spa

    Quote Originally Posted by wpgswim View Post
    Thanks for the feedback!

    I will trust my Taylor test numbers. It just seems weird that the dealer test is so "off" on the pH and TA. Any thoughts on why this might be?

    For a party...given CYA 30, would a FC of 8-10 ppm seem reasonable as a starting point? If so, guidelines I've read for FC of between 3-5ppm seems to go out the window. Thanks for helping me understand.
    For a CYA of 30 we would normally recommend keeping the FC between 4 - 6. Before a big party 8 - 10 would not be unreasonable.
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    Re: TFPC for Swim Spa

    Quote Originally Posted by tim5055 View Post
    For a CYA of 30 we would normally recommend keeping the FC between 4 - 6. Before a big party 8 - 10 would not be unreasonable.
    Great info! Thanks.

    As for the MA addition, it sure doesn't take much to impact things. As it stands now;
    FC - 3
    CC - 0
    pH - 7.6
    TA - 50
    CH - 170
    CYA ~ 30
    Borates ~ 40
    Arctic Ocean Swim Spa - Acrylic and Fiberglass - 5,500 ltr (1,453 US gals)
    Taylor K-2006 and K-1004 test kits

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    Re: TFPC for Swim Spa

    Yesterday we had a nice sunny warm day and I decided to do an experiment.
    My test results before the experiment were;
    FC - 7.5 (we had company over the night before and added extra liquid chlorine. This reading was expected)
    CC < 0.5
    pH - 7.7
    TA - 60
    CH - 170
    CYA ~ 30 (pool store tested at 33ppm 3 days ago)
    Borates ~ 40
    Temp - 101F

    I left the swim spa cover open from 9am to 2pm (5 hrs). I was in and out for a total of 90 mins during this time, swimming and soaking.

    At 2pm I retested just the FC and it read 0.5 . This really surprised me to which I have a few questions.

    Why did my FC dissipate so quickly? I do have an ozonator and the cover was open to direct sunlight. The pumps were on for approximately 2 of the 5 hrs.
    Is this type of FC loss to be expected? I have no significant CC therefore assume nothing bad is "growing" and eating the FC.
    Would a higher CYA level help reduce the FC loss? Should I consider using Dichlor for a bit to raise the CYA level, and if so what CYA level should I target?
    Are there any other considerations I should be aware of.

    My reason for the experiment is that this will be a typical weekend day over the summer, and likely with a higher swimmer load. I want to be prepared to manage the water safely and effectively.

    Any insight would be greatly appreciated.
    Arctic Ocean Swim Spa - Acrylic and Fiberglass - 5,500 ltr (1,453 US gals)
    Taylor K-2006 and K-1004 test kits

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    Saint George, KS
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    Re: TFPC for Swim Spa

    Quote Originally Posted by wpgswim View Post
    Yesterday we had a nice sunny warm day and I decided to do an experiment.
    My test results before the experiment were;
    FC - 7.5 (we had company over the night before and added extra liquid chlorine. This reading was expected)
    CC < 0.5
    pH - 7.7
    TA - 60
    CH - 170
    CYA ~ 30 (pool store tested at 33ppm 3 days ago)
    Borates ~ 40
    Temp - 101F

    I left the swim spa cover open from 9am to 2pm (5 hrs). I was in and out for a total of 90 mins during this time, swimming and soaking.

    At 2pm I retested just the FC and it read 0.5 . This really surprised me to which I have a few questions.

    Why did my FC dissipate so quickly? I do have an ozonator and the cover was open to direct sunlight. The pumps were on for approximately 2 of the 5 hrs.
    Is this type of FC loss to be expected? I have no significant CC therefore assume nothing bad is "growing" and eating the FC.
    Would a higher CYA level help reduce the FC loss? Should I consider using Dichlor for a bit to raise the CYA level, and if so what CYA level should I target?
    Are there any other considerations I should be aware of.

    My reason for the experiment is that this will be a typical weekend day over the summer, and likely with a higher swimmer load. I want to be prepared to manage the water safely and effectively.

    Any insight would be greatly appreciated.

    The high temperature has an effect on chlorine loss, as well as sunlight. I read the following on http://sciencing.com/heat-sun-affect...ne-21723.html:

    THE EFFECTS OF LIGHT

    Free chlorine is lost when it reacts with bacteria and other organisms, but also when it is hit by sunlight. Chlorine forms hypochlorite ions in water, the molecule that is measured as free chlorine. When ultraviolet radiation from the sun hits hypochlorite, it breaks apart, releasing the chlorine as gas to the atmosphere. Sunlight is so effective in reducing chlorine that a bright sunny day can reduce the chlorination level of a pool by 90 percent in just two hours. Pool maintenance workers add chlorine daily and use chemical stabilizers to prevent this loss.
    THE EFFECTS OF TEMPERATURE

    Temperature has an effect on chlorine breakdown, but the effect is indirect. Many bacteria species grow better in warmer water, and when bacteria proliferate, free chlorine is used up more quickly as it kills them. A general rule of thumb is that you need to add twice as much chlorine to the pool to maintain an adequate free chlorine level for every 6 degrees Celsius (10 degrees Fahrenheit) rise in temperature above 26 degrees Celsius (80 degrees Fahrenheit). This is less important for pools than it is for spas, which are regularly operated at higher temperatures.

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    Mod Squad tim5055's Avatar
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    Re: TFPC for Swim Spa

    Quote Originally Posted by Nitecat View Post
    The high temperature has an effect on chlorine loss, as well as sunlight. I read the following on http://sciencing.com/heat-sun-affect...ne-21723.html:

    THE EFFECTS OF LIGHT

    Free chlorine is lost when it reacts with bacteria and other organisms, but also when it is hit by sunlight. Chlorine forms hypochlorite ions in water, the molecule that is measured as free chlorine. When ultraviolet radiation from the sun hits hypochlorite, it breaks apart, releasing the chlorine as gas to the atmosphere. Sunlight is so effective in reducing chlorine that a bright sunny day can reduce the chlorination level of a pool by 90 percent in just two hours. Pool maintenance workers add chlorine daily and use chemical stabilizers to prevent this loss.
    THE EFFECTS OF TEMPERATURE

    Temperature has an effect on chlorine breakdown, but the effect is indirect. Many bacteria species grow better in warmer water, and when bacteria proliferate, free chlorine is used up more quickly as it kills them. A general rule of thumb is that you need to add twice as much chlorine to the pool to maintain an adequate free chlorine level for every 6 degrees Celsius (10 degrees Fahrenheit) rise in temperature above 26 degrees Celsius (80 degrees Fahrenheit). This is less important for pools than it is for spas, which are regularly operated at higher temperatures.
    In the first paragraph they do not take the effects of CYA into account in protecting the chlorine from the UV of the sun.

    In the second paragraph, we advocate regular testing and adjustment of the FC to the recommended levels. We do not advocate doubling chlorine levels as a "rule of thumb".

    I see you are new to TFP and we normally recommend reading in Pool School have you read? Start with these:
    ABCs of Water Chemistry
    Recommended Pool Chemicals
    How to Chlorinate Your Pool

    So, welcome to TFP!!
    TFP Moderator

    Trouble Free Pool is a free resource. The people who answer questions are volunteers. If you find the site to be a good resource, please consider making a donation to help support the site. Thanks.

    Support the site

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