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Thread: Cyanuric Acid does go down right?

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    Cyanuric Acid does go down right?

    Hi all, first post here, been browsing the site since I bought a home with a pool 2 years ago.

    I have always had a pool service come put chemicals in my pool, at $50 a month I thought it was reasonable, but after an algae bloom this past Easter Sunday, I am going to let them go as this was the second time in a year this happened. Each time it did, I tested the water (with HTH strips) and sure enough the free chlorine (FC) was zero.

    So now on to my question.

    As of right now my CYA level is 30-50 (strips, yes I know, im ordering the TFT-100)
    With lots of sun on the pool, How much will my CYA reduce weekly?
    Why do I care? Because I would like to use trichlor tablets and trichlor shock.
    Why would I do such a terrible thing? Long story short, I can get it at a very discounted rate, much cheaper than liquid Cl bleach.

    My pool gets a lot of sun, full sun from 7am to around 4pm, then half sun from 4-7ish (730ish is around sunset right now).

    I would like to use the tablets for convenience and cost, but would the amount added considerably outweigh the amount lost to UV penetration?

    TIA

    FWIW pool service used liquid chlorine and copper algaecide.
    ~22,000 gallon inground plaster pool, 1 skimmer, 3 return jets
    Irregular pool sized approximately 19' x 40' 9' deep, Color Splash 3G pool light
    Pentair Clean & Clear Plus cartridge filter (part# 160301)
    1 HP Pentair Pump Model WFE-24 single speed
    Light Blue Pool Cover BBB Method

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    Re: Cyanuric Acid does go down right?

    Nope, it does not go down unless you remove water, unless some really weird circumstances occur.

    Am I reading your post right, you have an above ground plaster pool?
    Built in 1957 44,000 gallon in-ground, Wet Edge Primera Stone in Sky Blue, Intelliflo VF Pump, 600 lb. Pentair Triton II TR-100 Sand Filter, CircuPool RG 60 Plus SWG, TF-100 test kit
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    Re: Cyanuric Acid does go down right?

    That was a silly mistake, in ground pool! I fixed the sig.

    For the CYA, I have read here and other places that sunlight breaks it down, why else would you have to add more eventually? Where I live, removing water is definitely not an option.
    ~22,000 gallon inground plaster pool, 1 skimmer, 3 return jets
    Irregular pool sized approximately 19' x 40' 9' deep, Color Splash 3G pool light
    Pentair Clean & Clear Plus cartridge filter (part# 160301)
    1 HP Pentair Pump Model WFE-24 single speed
    Light Blue Pool Cover BBB Method

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    mrcarcrazy's Avatar
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    Jan 2014
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    Odessa, TX
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    Re: Cyanuric Acid does go down right?

    Sun Doesn't break down CYA.
    IG gunite/plaster pool/spa Started 1/17/14, Plastered 5/16/14
    Size: 12'-21'x39' free form, depth ranging from 4' to 7, attached 6 person spa with spillover.
    Equipment: Whisperflo 2hp pump, Pentair 30" sand filter, Pentair Mastertemp 400k BTU heater, 1hp Whisperflo for waterfalls, and a blower for spa floor

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    Re: Cyanuric Acid does go down right?

    You would only add CYA due to:
    LOTS of backflushing, which you won't do with a cart filter
    LOTS of splash-out

    That's about it.

    If you can't remove water, you need to stay on a "liquid diet", or go to salt water chlorination. Tabs or granules are not going to be your friend.
    Built in 1957 44,000 gallon in-ground, Wet Edge Primera Stone in Sky Blue, Intelliflo VF Pump, 600 lb. Pentair Triton II TR-100 Sand Filter, CircuPool RG 60 Plus SWG, TF-100 test kit
    If TFP has helped you, please click to SUPPORT TFP!

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    Re: Cyanuric Acid does go down right?

    CYA protects chlorine from being broken down by the sun ... but CYA is not broken down by the sun.

    ** Does not mean that chlorine is completely protected - chlorine still needs to be replenished
    SwimNPlay AG 15x33 oval 48" high 12k gallons - Used pool set up July 2013
    Hayward sand filter, Sta-Rite 3/4 HP pump
    Kleen Machine Robot, TF-100 test kit
    Central NC

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    Re: Cyanuric Acid does go down right?

    ****.

    Thanks for the prompt replies. Ok, time to start shopping for NaClO
    ~22,000 gallon inground plaster pool, 1 skimmer, 3 return jets
    Irregular pool sized approximately 19' x 40' 9' deep, Color Splash 3G pool light
    Pentair Clean & Clear Plus cartridge filter (part# 160301)
    1 HP Pentair Pump Model WFE-24 single speed
    Light Blue Pool Cover BBB Method

  8. Back To Top    #8

    Re: Cyanuric Acid does go down right?

    Add one of the recommended test kits to your shopping list - it will be key in determining what you need to add to your pool.
    SwimNPlay AG 15x33 oval 48" high 12k gallons - Used pool set up July 2013
    Hayward sand filter, Sta-Rite 3/4 HP pump
    Kleen Machine Robot, TF-100 test kit
    Central NC

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    Mod Squad jblizzle's Avatar
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    Re: Cyanuric Acid does go down right?

    The other way to reduce the CYA (and CH) in the water is through hiring a RO service company, but only available in limited areas and generally cost more than just replacing water.

    To be fair ... CYA does slowly get "consumed", but I think it is something like under 5ppm per month during the summer. In any case, exclusive use of tablets and granular chlorine is rarely going to be a good idea.
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
    500 sqft Heliocol solar panels, ThePoolCleaner, TF-100 test kit w/ SpeedStir
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  10. Back To Top    #10

    Re: Cyanuric Acid does go down right?

    I have 25 lbs of trichlor tablets, which are effectively free, because I already paid for them. However, it's still cheaper for me to use bleach, because I don't want to pay to replace water. I'll use them eventually, at least some of them.
    20,000 gal in-ground plaster pool with sand filter. Replastered recently. Mostly adding bleach and acid. CYA was high when I took over.

  11. Back To Top    #11

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    Thomson GA
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    Re: Cyanuric Acid does go down right?

    Keep them for a time when you go on vacation and can't add chlorine manually. Regular sage will get your CYA so high that you will not be able to keep enough chlorine in the pool. The CYA/Chlorine chart http://www.troublefreepool.com/conte...art-slam-shock shows that as the CYA increases they amount of chlorine PPM needed to sanitize the pool increases. I had an Intex pool and it happened to me.
    Gerry
    27' x 54" AG Salt Water Pool Installed 2014, Hayward 23" Sand Filter, 1 HP 2-Speed Power-Flo Matrix Pump, AQ-TROL SWG, TF-100 Test Kit

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