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Thread: Why not use Trichlor tablets if CYA is low?

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    Why not use Trichlor tablets if CYA is low?

    In this article on how to chlorinate your pool
    pool-school/types_chlorine_pool
    It says not to use Trichlor tablets because of the CYA. If your CYA is low, is there any reason not to use them?
    36 x 18 oval pool, inground, plaster pool.
    27000 gallons
    1 hp pump. Sand filter
    Pool built in 1971.

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    Mod Squad JohnT's Avatar
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    Re: Why not use Trichlor tablets if CYA is low?

    They are fine with low CYA, but don't underestimate how quickly they add CYA. In my pool, I gain about 7.5ppm per week CYA with trichlor tabs.
    TFP Moderator
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    Re: Why not use Trichlor tablets if CYA is low?

    Thanks for the info. I'll test weekly.
    36 x 18 oval pool, inground, plaster pool.
    27000 gallons
    1 hp pump. Sand filter
    Pool built in 1971.

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    Re: Why not use Trichlor tablets if CYA is low?

    Boy Tom you sure like post seperate topics (it is generally helpful to keep things in one thread unless they are totally seperate topics )

    Since you pH is so low, trichlor is not the best choice for you since it lowers ph and TA in addition to raising CYA. If you are going to use Trichlor, get the ph and TA up and watch it closely!
    TFP Expert who uses Pool School and my TF100 test kit along with PoolMath for my: Round 11K gallon AGP with deep end, 20" sand filter, Matrix 1hp 2spd, 6 2ftX20ft solar panels (and solar cover!), Intex SWCG (copper bars disconnected) and a Rubadub hot tub (chlorine). The SLAM process is not finished until: 1. CC < 0.5 ppm, 2. An OCLT < 1.0 ppm and, 3. The water is crystal clear.

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    Re: Why not use Trichlor tablets if CYA is low?

    Tom,

    Linen brings up a very good point for all of us to remember. Keep your info together in one thread as much as possible. By itself, your question of CYA is answered one way but, when considering your low pH, the answer is really somewhat different.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Re: Why not use Trichlor tablets if CYA is low?

    As far as the tablets go, more than a few people have considered us as being anti stabilized chlorine here at TFP. This is not the case though. Many of us use trichlor and other forms of stabilized chlorine without issues. Where people run into problems is when they don't realize the problems that can develop with high CYA from using dichlor and trichlor. As long as you know what is happening in your water and you know this by testing regularly and you take steps to prevent CYA from getting too high, there is no reason why stabilized chlorine sources could not be used.

    As linen said, trichlor does lower pH and if you are already running a low pH (or low TA), trichlor may not be the best thing to use at this time.

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    Re: Why not use Trichlor tablets if CYA is low?

    Boy Tom you sure like post seperate topics (it is generally helpful to keep things in one thread unless they are totally seperate topics )
    and

    Linen brings up a very good point for all of us to remember. Keep your info together in one thread as much as possible
    Will do. Just tell me how you want me to post and I'll be happy to do it. I don't have much experience in this.

    Should I just ask all future chemical questions in this topic?
    36 x 18 oval pool, inground, plaster pool.
    27000 gallons
    1 hp pump. Sand filter
    Pool built in 1971.

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    Re: Why not use Trichlor tablets if CYA is low?

    After adding some chemicals today, here are my current test results

    Total chlorine 3.5
    Free Chlorine 3.5
    pH 7.6
    Total Alkalinity 50
    Calcium hardness 50 - I made a mistake when I tested yesterday and said it was 100
    CYA 10

    The thing I am most concerned about is the low calcium, since it can damage my plaster. I bought a bag but the guy at the pool store told me I could not add it in cold weather because it would not dissolve. Is this correct and is there any way around this?
    36 x 18 oval pool, inground, plaster pool.
    27000 gallons
    1 hp pump. Sand filter
    Pool built in 1971.

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    Re: Why not use Trichlor tablets if CYA is low?

    Sure, keep it here for now. What one thread does is tell your "story" so others can see what has happened as you go along.

    Sometimes it will be completely obvious to start a new thread but, if you're in doubt, keep it together.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Re: Why not use Trichlor tablets if CYA is low?

    Concerning adding calcium in cold weather, I just found this pool site which said the exact opposite of what the pool store guy said. It says:

    Calcium minerals dissolve quicker in cold temperatures. When the pool is heated up, the high amounts of CH become visible, as the calcium takes much longer to dissolve.
    http://www.swimtownpools.com/swimtowns- ... -s/774.htm

    Which is correct? I would like to add the calcium as soon as possible. Tomorrow the high in Atlanta is supposed to be 60, the low 34.
    36 x 18 oval pool, inground, plaster pool.
    27000 gallons
    1 hp pump. Sand filter
    Pool built in 1971.

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    Re: Why not use Trichlor tablets if CYA is low?

    I have never heard that you shouldn't add calcium in the cold. I honestly don't know. Calcium chloride seems to dissolve on ice, when used as a deicer ( not that we have a lot here). Was the "pool store" a national chain or local outfit? If it's the chain, they have a reputation for misinformation.
    My cement pond is a 36K gunite 20X40 built in mid 1960s, Hayward S244S filter, Aquarite SWCG, Jandy 1.5HP 2sp, TF-Test kit and Nitro Wall Climber

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    Re: Why not use Trichlor tablets if CYA is low?

    Was the "pool store" a national chain or local outfit?
    It was a local outfit, but that doesn't mean the guy couldn't make a mistake. I guess I'll do a test and see how a little bit dissolves in a bucket of pool water.
    36 x 18 oval pool, inground, plaster pool.
    27000 gallons
    1 hp pump. Sand filter
    Pool built in 1971.

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    Re: Why not use Trichlor tablets if CYA is low?

    Tom:
    According to Michigan State University (MSU Pesticide Safety Education Program) it is the exact opposite of what you were told, if the water gets warmer, calcium carbonate becomes less soluble.

    From http://www.pested.msu.edu/Resources/bul ... 1chap6.pdf :

    "Temperature: The higher the temperature of the pool water, the less soluble calcium carbonate becomes. In most cases water
    temperature cannot be kept constant due to unpredictable weather and environmental conditions. As a pool operator, be aware of this and monitor
    the temperature when other water parameters are checked. Keep in mind the influence temperature has on the calcium carbonate levels—warmer water, less soluble; colder water, more soluble"
    My cement pond is a 36K gunite 20X40 built in mid 1960s, Hayward S244S filter, Aquarite SWCG, Jandy 1.5HP 2sp, TF-Test kit and Nitro Wall Climber

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    Re: Why not use Trichlor tablets if CYA is low?

    Quote Originally Posted by TomAtlanta
    Was the "pool store" a national chain or local outfit?
    It was a local outfit, but that doesn't mean the guy couldn't make a mistake. I guess I'll do a test and see how a little bit dissolves in a bucket of pool water.
    Yep, I had to read the statement a couple of times (the MSU statement), it seems backwards.

    Be careful handling calcium, it will get warm fast, use gloves and glasses.
    My cement pond is a 36K gunite 20X40 built in mid 1960s, Hayward S244S filter, Aquarite SWCG, Jandy 1.5HP 2sp, TF-Test kit and Nitro Wall Climber

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    Re: Why not use Trichlor tablets if CYA is low?

    I have calcium chloride flakes. I did a test. I added a cup to a bucket of pool water, stirred it up and counted how many stirs it took to dissolve. I repeated with a bucket of warm water. I did it all again using two cups of calcium. I could not tell any difference in how fast it dissolved in the warm tap water, and the cold pool water. The other variable could be the chemical difference of the tap water and pool water.
    36 x 18 oval pool, inground, plaster pool.
    27000 gallons
    1 hp pump. Sand filter
    Pool built in 1971.

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    Re: Why not use Trichlor tablets if CYA is low?

    Be careful handling calcium, it will get warm fast, use gloves and glasses
    What do you mean it will get warm fast?

    I just was using it. I don't think I got any on my skin, but I washed my hands afterwords. There were some fumes when I stirred it up in the bucket and I breathed a little of that and can still taste it a little in my mouth but don't feel bad.
    36 x 18 oval pool, inground, plaster pool.
    27000 gallons
    1 hp pump. Sand filter
    Pool built in 1971.

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    Re: Why not use Trichlor tablets if CYA is low?

    So I threw some of the calcium flakes into the deep end. I watched them settle to the bottom. They gradually dissolved. It took about 2 minutes. The guy at the pool store obviously doesn't know what he is talking about. Thanks for your help.
    36 x 18 oval pool, inground, plaster pool.
    27000 gallons
    1 hp pump. Sand filter
    Pool built in 1971.

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    Re: Why not use Trichlor tablets if CYA is low?

    Quote Originally Posted by TomAtlanta
    Be careful handling calcium, it will get warm fast, use gloves and glasses
    What do you mean it will get warm fast?

    I just was using it. I don't think I got any on my skin, but I washed my hands afterwords. There were some fumes when I stirred it up in the bucket and I breathed a little of that and can still taste it a little in my mouth but don't feel bad.
    I am using calcium chloride, it looks like granules. If you grab a handful, it gets warm, or so it seems. I have used it to melt ice. You are using something I am not familiar with. Sorry if I caused any confusion. Just be cautious/safe.

    Well, it sounds like you have it figured out and if it stays warm maybe swimming soon.
    My cement pond is a 36K gunite 20X40 built in mid 1960s, Hayward S244S filter, Aquarite SWCG, Jandy 1.5HP 2sp, TF-Test kit and Nitro Wall Climber

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    Re: Why not use Trichlor tablets if CYA is low?

    Go ahead and add your calcium.

    Some chemicals create heat when dissolved in water. Calcium chloride is one of them.

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    Re: Why not use Trichlor tablets if CYA is low?

    I added chemicals this morning and these are my current readings, taken 4 hours after adding chemicals:

    ph 7.7
    TA 60
    CH 70
    TC 3.5
    CYA 10

    I just added more calcium to get the CH higher
    I know the TA needs to go up, but adding more baking soda will also raise the ph too high. Which is worse, high ph or low TA?
    36 x 18 oval pool, inground, plaster pool.
    27000 gallons
    1 hp pump. Sand filter
    Pool built in 1971.

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