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Thread: Why Use Chlorine Tabs If It Always Leads to High CYA?

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    Arrow Why Use Chlorine Tabs If It Always Leads to High CYA?

    Hello guys/gals,


    So I've been reading a lot on the forum to figure out why there is always still some black spots that look like dead algae at the bottom of my pool that I would have to vacuum up.

    I guess my question is, why or when do we use chlorine tablets and other granulating stuff, knowing they will all eventually lead to the CYA being too high and have to drain the water?

    I test the chlorine levels and it reads "2" on the Poolmaster kit and "0" on the test strips.

    CYA is sky high at 100 or more. I'm pretty sure it is from the chlorine tabs and granulating chlorine powder from Leslie's.

    I'm new to pool ownership and when I bought this house with a green pool, the Leslie guy told me to use those items and stack the floater full of 3" tabs. After the pool cleared, I'm trying to balance the water now and the CYA reading is way too high.

    Advice?

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    Re: Why Use Chlorine Tabs If It Always Leads to High CYA?

    I've been in your boat. The mentality on this forum is anti-pool store. You need to fully read through every page/part of Pool School to understand the methodology of what they call the TFPC method.

    Your first change is to use the right type of test kit. Order a Taylor K-2006 OR what most people recommend here, the TF-100. Then you'll know you're getting accurate results.

    You're right, don't use the chlorine tabs. According to the methodology here, you're replacing that with chlorine bleach...yup, the stuff you can buy at the grocery store. The upside, it won't have any additives and it costs less, the downside (from what I can tell) is it's more of a pain to deal with because it's heavy liquid plus you should be testing/adjusting daily.

    At this point if your CYA is high, you can adjust what your chemical balance should be, but you'll end up using a lot more bleach and it make sense to drain the water in order a certain percentage to bring your CYA down. You would use PoolMath in order to figure out what you need of each type of chemical. Just make sure you're filling everything out accurately based on numbers you get from one of the two test kits I mentioned.
    ~21,000 gal, IG Vinyl w/Liner, Hayward Pro-Grid DE2420 DE filter, Built: ~2002, manual vacuum, K-2006 Test Kit

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    Re: Why Use Chlorine Tabs If It Always Leads to High CYA?

    The answer to the question is, I never use tabs. Don't have any, won't buy any. When I refilled my pool I used dichlor powder, but I closely monitored the effects of what it added to the pool using PoolMath at the top of this page and through my test results. Once CYA got to where I wanted it, I fired up the SWG and gave away what I had left of the dichlor, to a friend filling his 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: Why Use Chlorine Tabs If It Always Leads to High CYA?

    Thanks for the reply guys. I have been reading the pool school info and other threads on here. And that's why it makes no sense to me that tabs are probably the most common way for people to chlorinate their pools. Even the pool maintenance guys I've seen uses tabs to maintain pools for their clients. Just makes no sense to me.

    BTW, is there any other way to lower the CYA other than to drain half the pool?

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    Re: Why Use Chlorine Tabs If It Always Leads to High CYA?

    There is no other way to get rid of CYA other than drain.

    What's worse is those pool maintenance guys are bad about putting them in the skimmer. Keep in mind, they don't care if your pool is balanced, they want you to have a reason to call them.
    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: Why Use Chlorine Tabs If It Always Leads to High CYA?

    Quote Originally Posted by Foody View Post
    that's why it makes no sense to me that tabs are probably the most common way for people to chlorinate their pools.
    One arguement for the trichlor pucks is for when your CYA levels are lower than your target.
    For example, I recently drained my pool, and I added CYA to get to around 30-40ppm and then let the tabs get me to 50-60 (high sun load) before I pull them and go to straight liquid chlorine (and periodic muriatic acid).

    Quote Originally Posted by Foody View Post
    is there any other way to lower the CYA other than to drain half the pool?
    There are other options, but the best is to drain & refill as needed.
    Silicon Valley, 38,500 gallons in-ground plaster; Sta-Rite System 3 Model S8M150, 259 sqft cartridge 25022-0203S + 191 sqft cartridge #25021-0202S = 450 sqft filter@0.28gpm/sqft = 125 gpm@50psi max. Three 220v Sta-Rite Max-e-Glas II pumps {AO Smith QC1102 1.0x1.65SF for filter + cleaner; SQ1152 1.5x1.47SF for spa jets; square 48Y flange}. 13 Fafco 12'x4' professionally installed "Revolution" solar heating panels + Raypak RP2100 P-R 405A-EP LPG 399,000/hour heater + Compool Lx3600 controller + Infinity 4000 automatic pool cover (120v 3/4 HP motor); both skimmers are NOT filtered & serve only as intake for 9-port water valves (aka cleaner heads) controlling fifteen Paramount PCC2000 3" self-cleaning jets with the optional Debris Containment Canister.

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    Re: Why Use Chlorine Tabs If It Always Leads to High CYA?

    Tabs are pretty convenient, particularly if you are going to be away for a couple of days and want to toss them in a floater. Just know how they will impact your chemistry. Before I knew what I was doing I actually bought a huge bucket of those pucks so I will tend to use them at the beginning of the season, when my CYA is low due to the partial drain of winter close.

    There is no real other practical way to lower CYA other than water replacement, though some on this board mention the legendary reverse osmosis treatment, I believe it is only available in like one county in CA.
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    Re: Why Use Chlorine Tabs If It Always Leads to High CYA?

    If you have more than a 3 day gap between being able to care for your pool, then tablets are a must. You can get away with using more if you have more splash out (which means the pool is being used, so it needs more CL anyway) or if you have filter that requires backwashing. I am able to get by with just bleach in the winter (6 months), so at least the CYA does not build then.

    I have to use a few in my semi-public pools, luckily they are sand filters, so I backwash more water than necessary for a filter clean to keep the CYA at bay.
    2013 20x40 Vinyl Ingound Pool. 30K Gallons. Hayward Aqua Rite Chlorine Generator. Hayward C-3030 Cartridge Filter. 1.5 HP Pentair Pump. Pentair Magic Stream II Deck Jets. Pool Automation=Allen-Bradley PLC 5/04. TF-100 Test Kit.

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    Re: Why Use Chlorine Tabs If It Always Leads to High CYA?

    The tablets are convenient, that's why.

    People in other parts of the country get their pools diluted with rain water in the summer. We don't even get that in the winter! Then they drain a lot out before they close the pool for the season. We don't close. So it's conceivable that someone could maintain a pool with pucks for their whole 12 or 14 week swim season and not suffer from CYA buildup. But not in SoCal.

    I use pucks when I'm out of town for a few days at a stretch. I also use pucks on a fairly regular basis because 1) I need chlorine like we all do; 2) The high TA water requires a lot of acid to control pH and pucks are acidic; 3) I lose CYA when I do partial drains to lower the CH buildup and pucks replace it.

    There is no official "pucks are bad, m'kay" mantra here. Any source of chlorine is acceptable, provided you know what you're adding and you need it. Most people - even most pool store employees - don't understand the FC/CYA relationship. They don't necessarily know what they're adding or if they need it. No one has explained that while some is good, more is not always better.
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    Re: Why Use Chlorine Tabs If It Always Leads to High CYA?

    Oh yes, if you need the "side-effect" of the lower pH, then pucks are nice for that.

    I try to use "side effects" to my advantage to keep from adding unnecessary chems to the pools.
    2013 20x40 Vinyl Ingound Pool. 30K Gallons. Hayward Aqua Rite Chlorine Generator. Hayward C-3030 Cartridge Filter. 1.5 HP Pentair Pump. Pentair Magic Stream II Deck Jets. Pool Automation=Allen-Bradley PLC 5/04. TF-100 Test Kit.

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    Re: Why Use Chlorine Tabs If It Always Leads to High CYA?

    FWIW, my father used pucks (actually, they were sticks, IIRC) for about 15 years that he had a pool and never had algae or even cloudy water that I recall.

    He replaced enough water through backwashing (he had sand filters), rain, splash-out, etc. that he must have kept the CYA at a reasonable level. Our pool was always crystal clear.

    That said, knowing what I know now, I would never use pucks as a long term chlorine source.
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    Re: Why Use Chlorine Tabs If It Always Leads to High CYA?

    Does anyone if refilling through evaporation will eventually lower the CYA? Because in the evaporation is fairly high where I'm at and I almost have to refill daily.

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    Re: Why Use Chlorine Tabs If It Always Leads to High CYA?

    Quote Originally Posted by Foody View Post
    Does anyone if refilling through evaporation will eventually lower the CYA? Because in the evaporation is fairly high where I'm at and I almost have to refill daily.
    No, it does not.
    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
    Troublefree does not mean Maintenancefree. It's like brushing your teeth: You can spend a couple minutes a day and pennies a week or go to the dentist once a year and spend several thousand dollars.
    A pool is like a pet - you have to feed it every day, even the days you don't want to play with it!

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    Re: Why Use Chlorine Tabs If It Always Leads to High CYA?

    Quote Originally Posted by Richard320 View Post
    No, it does not.
    Richard, how much liquid chlorine are you putting into your pool per week? Just want to know for reference since we are in similar areas and weather.

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    Re: Why Use Chlorine Tabs If It Always Leads to High CYA?

    About 2 gallons of 12.5%
    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
    Troublefree does not mean Maintenancefree. It's like brushing your teeth: You can spend a couple minutes a day and pennies a week or go to the dentist once a year and spend several thousand dollars.
    A pool is like a pet - you have to feed it every day, even the days you don't want to play with it!

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    Re: Why Use Chlorine Tabs If It Always Leads to High CYA?

    Quote Originally Posted by Richard320 View Post
    About 2 gallons of 12.5%
    Thanks, whats a good place to buy the 12.5%? I've been using Kem-Tek from Lowes at 10% for about $6.86 for 2 gallons.

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    Re: Why Use Chlorine Tabs If It Always Leads to High CYA?

    Quote Originally Posted by Foody View Post
    Thanks, whats a good place to buy the 12.5%? I've been using Kem-Tek from Lowes at 10% for about $6.86 for 2 gallons.
    http://www.hasapool.com/dealer_locator_hasa.php
    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
    Troublefree does not mean Maintenancefree. It's like brushing your teeth: You can spend a couple minutes a day and pennies a week or go to the dentist once a year and spend several thousand dollars.
    A pool is like a pet - you have to feed it every day, even the days you don't want to play with it!

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    Re: Why Use Chlorine Tabs If It Always Leads to High CYA?

    At the end of last summer, my cya was at least 150. All winter long, I was dreading this summer and having to drain my pool. BUT; this summer my cya dropped to 20 over the winter. So I guess it's possible to get rid of cya without draing your pool
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    Re: Why Use Chlorine Tabs If It Always Leads to High CYA?

    Quote Originally Posted by Thesil View Post
    At the end of last summer, my cya was at least 150. All winter long, I was dreading this summer and having to drain my pool. BUT; this summer my cya dropped to 20 over the winter. So I guess it's possible to get rid of cya without draing your pool
    some have reported this before and it has usually been attributed to a bacteria possible converting the CYA to ammonia IIRC. Did you happen to have high CC when you opened it?
    TFP Moderator 39 X 18 23,000(ish) freeform gunite; built 2007ish; Pentair Triton II TR100 600lb Sand filter; 2 HP Pentair pump with 2.2 HP AO Smith single speed motor; 2 skimmers, 1 main drain, 4 returns w/waterfall, Stenner 45MHP2 3GPD running@ 60% - 15 gal Tank; heated by the sun CYA 200+ when I started - 50 now. Dolphin Supreme M5 Pool Cleaner. Hot Springs SX Spa, 285 gallon

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    Re: Why Use Chlorine Tabs If It Always Leads to High CYA?

    CYA does vanish in some cases, especially over the winter. Sadly there is no known way to get that to happen on demand.
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