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Thread: FC, High CYA, algae and tri-chlor

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    FC, High CYA, algae and tri-chlor

    Hi. My first post. I have a 22,000 gallon marcite pool, evaporation refill by alkaline well water. I have to add about a gallon of muriatic acid each week. But, I digress.

    Since the pool was filled, 12 years ago, about 1,000 pounds of tri-chlor tablets have been dissolved in it. Leslie's tells me my CYA is 90 and my FC is 2 (which on their report states OK!) However, algae is sometimes a problem.

    Recently I slammed the pool with 7 gallons of 10% Sodium Hypochlorite liquid. Looks great!

    I read that (and calculated on poolcalculator.com) with my I need a FC level of about 7 to 12 in order to keep algae away. I also read that maintaining this FC level is impossible with tri-chlor tablets. Is this true?

    Question: With a CYA level of 90, how can I maintain a FC level of 7 to 12 with tri-chlor tablets? If I can't, what are my options?

    Draining and refilling the pool is not a financially viable option.

    Using the Leslie's CYA lowering stuff sounds like a nightmare.

    Thanks!
    Jim

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    Mod Squad Texas Splash's Avatar
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    Re: FC, High CYA, algae and tri-chlor

    Hello Jim and welcome to TFP!
    With a CYA level of 90, how can I maintain a FC level of 7 to 12 with tri-chlor tablets? If I can't, what are my options?
    You really can't. Each tab will continue to drive-up CYA higher, thereby requiring more FC. What to do? ... Stick to regular bleach and feed your pool each day or evening. Don't use anymore tabs or bags of shock from the pool store. Regular bleach is the best sanitizer. Now keep in mind your CYA may be higher than 90 if it was tested at the pool store, so you may need to increase your FC a bit more. If you're not using a TF-100 or Taylor K-2006C test kit of your own, that really needs to be priority #1 Jim. There is no substitute for testing your own water with one of those kits.

    Confirm your CYA and stay close to the Pool School - Chlorine / CYA Chart and you should see some improvement over time. Nice to have you join us.
    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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    Re: FC, High CYA, algae and tri-chlor

    Jim,

    Welcome to TFP... This is a great place to be..

    The reason you can't keep using tablets, is because the more tabs you use, the higher the CYA becomes. It is a never ending cycle. I'm surprised that if you have been using tabs for 12 years that your CYA is not much, much, higher. I suspect that you have drained your pool in the past. If you have read anything here, you already know that we do not trust any reading from the pool store. The TFP approach is for the homeowner to test his own pool water and then using the results of the tests to maintain a chemical balance by only adding what is needed, not what the pool store wants to sell you. This works for me and thousands of others. There is no need to go to the pool store again, no need to "shock" your pool weekly, or ever.

    Instead of using tabs, the TFP approach is to use either liquid chlorine or a Salt Water Chlorine Generator (SWCG). You can add liquid chlorine manually, which works fine, but requires a little more daily maintenance, or you can use a Stenner pump system, which automatically adds chlorine from a plastic tank.

    If you have not done so already, please use the link at the top of this page and read all you can in "Pool School".

    Thanks,

    Jim R.
    Finished in 2015 - 17K Gal, IG, 20' x 25' Almost Rectangular Pool, Pebble finish, three rockport water falls. Pentair Equipment: EasyTouch 4, IC40 SWG, 3 HP VS Pump, CCP520 Cartridge Filter.
    TF100 with SpeedStir and SampleSizer, ColorQ Pro 7, Dolphin Premier Robot Cleaner, added Screen Logic 2, added small 3 person Calder Spa.

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    Re: FC, High CYA, algae and tri-chlor

    Thank you. Unfortunately, my conclusions were correct. I just bought (online, and had shipped to me, and have received) 100 pounds of tabs! I read this thread: Cost Comparison of Chlorine Sources and decided that tabs were definitely the way to go (100 pounds for $170) because the pool store charges $4.50 a gallon for 10% sodium hypochlorite.

    Hmm... Craigslist?

    Jim

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    Mod Squad Texas Splash's Avatar
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    Re: FC, High CYA, algae and tri-chlor

    You can "try" to return the unopened tabs. Or perhaps try to get on-line store credit for one of their other products? When it comes to sodium hypochlorite, any regular bleach will do. Check around in your area, I believe there may some bulk providers as well that provide a good bargain. For me personally, I hit the grocery store every weekend and pick-up 3 gallons or so of regular 8.25% bleach and I'm set for the week.
    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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    Re: FC, High CYA, algae and tri-chlor

    Hi Jim,
    Thanks for the further advice. Yeah, the pool store wants to sell me all sorts of stuff!
    I haven't drained my pool. As I'm on a well, I had to fill it with water trucks in 2004. It refills automatically from the well to replenish evaporation, which is very high in this dry climate of 15% humidity.
    I'm surprised, too, that the CYA is not higher.
    I'll get a proper test kit.
    What I've started doing last year, in the winter when it rains, is to drain the pool as low as I can while still allowing the pump to run and then allow it to refill from the rain. This gives me about 13,000 gallons of new rainwater each year. But, I only started last year. Maybe that was enough to get the CYA down to where it is.
    At least I'm going to take back that PhosFree which was forcibly sold to me the other day!
    Jim

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    Re: FC, High CYA, algae and tri-chlor

    Quote Originally Posted by Texas Splash View Post
    You can "try" to return the unopened tabs. For me personally, I hit the grocery store every weekend and pick-up 3 gallons or so of regular 8.25% bleach and I'm set for the week.
    Unfortunately, shipping 100 pounds back to the online retailer isn't an option. 84 pounds of tabs a year (what I've been using for 12 years) costs me about $143. Based on the cost of 8.25% bleach ($3.65) or 10% chlorine at the pool store ($4.95) I'd be paying a lot, lot more (I figure three times as much). However, if it's my only option, it's my only option.
    Last edited by JamesP; 09-25-2016 at 02:05 PM. Reason: more info

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    Mod Squad kimkats's Avatar
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    Re: FC, High CYA, algae and tri-chlor

    The stuff they try to sell to lower CYA does not work. Several people tried it and none of them got the results expected or wanted

    What I can't wait to see/hear is how clear you water is once we get it dialed in using TFP!

    I am going to share a set of links I put together for new pool owners and people new to TFP. It is a LOT of info. so take it a bite at a time. Once you get your test kit and start testing it will start to make sense.

    Print these out:
    Pool School - Basic Pool Care Schedule

    Pool School - Recommended Levels


    Bookmark these:
    Pool School - Recommended Pool Chemicals


    http://www.troublefreepool.com/calc.html


    Pool School - ABCs of Pool Water Chemistry


    Make sure to ask any and all questions you might have no matter how small! We have all been where you are at one point.

    For right now the most important one is ABC of pool Water. It is the corner stone to TFP. It tells you the whys and hows for maintaining a pool.

    TFP Moderator 33x52 round AG 25,600 gals Sand Filter 1.5hp Pump - 2 Speed, SLAM, Pool School, Recommended Levels, Recommended Chemicals, Pool Math, Chlorine/CYA Chart, TF-100 Test Kit

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    Re: FC, High CYA, algae and tri-chlor

    Thank you. I will read all there is to read at those links and follow the advice.

    My water? It's presently beautiful! It seems my only issue is going to be how to maintain an FC of 7 to 12 with such a high CYA.

    I'm wondering how much chlorine my pool will USE in a week with the CYA being so high. Just because I can dissolve 84 pounds of tabs in the pool per year and shock it now and then when algae appears, doesn't mean I'll need the equivalent amount of chlorine in liquid form.

    I'll get a test kit which can handle FC levels greater than 5 and also tests CYA levels. Then, I'll use liquid chlorine to maintain the appropriate FC level.

    Can you believe the pool store water analysis report showed a FC level of 2 to be OK with a CYA of 90? Makes one wonder...

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    Mod Squad Texas Splash's Avatar
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    Re: FC, High CYA, algae and tri-chlor

    No surprise on the pool store testing. We see many such irregularities at those places. As for your FC usage, with an elevated CYA your FC may hold considerably well once you increase it to the 10-12 mark. That is assuming there is no algae or organic matter in the water. Over time, with slow water replacement as allowed in your area, your CYA will slowly fall back to a more manageable level.

    As a reminder, remember that whenever your FC is over 10 (which your may be quite often), your pH will read (false) high, so don't let that throw you off too much. Whenever you need to do an accurate pH test, just make sure the FC is at 9 or lower.
    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.
    If you enjoyed your TFP experience, please consider donating to Support TFP!

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    Re: FC, High CYA, algae and tri-chlor

    Unfortunately, replacing water lost through evaporation will not lower the CYA level. The only way to lower it would be to replace water which I drain from the pool.

    What about the chlorine neutralizer I put in the test vial before doing a pH test? Won't that make the test accurate?

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    Re: FC, High CYA, algae and tri-chlor

    One more thing: if my CYA is 90 and my FC is 7 to 12, for how many tests at these levels will the TF-100 kit last? Seems like I'd run out of reagent very quickly!

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    Mod Squad Texas Splash's Avatar
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    Re: FC, High CYA, algae and tri-chlor

    There's a good discussion HERE about how long a bottle may last. In my estimate, I calculated as follows:
    - 25 drops = 1 ml
    - A 2 ounce R-0871 bottle = 59 ml.
    - So 25 drops x 59ml = 1475 drops per bottle.

    With a CYA of 90 and trying to maintain an FC of "12" (24 drops), 1475 total drops per bottle divided by 24 per test equals about 61 tests. That's assuming you use the 10 ml sample FC test. If you do the 5 ml water sample (not quite as accurate), with one drop per FC, it could last longer.

    That's my "wag" at it. I'll let the scientists confirm.
    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.
    If you enjoyed your TFP experience, please consider donating to Support TFP!

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    Re: FC, High CYA, algae and tri-chlor

    25 drops per ml? Well, I guess so! Thank you for pointing me to that post!

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    Mod Squad Texas Splash's Avatar
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    Re: FC, High CYA, algae and tri-chlor

    Yes, that's what I found searching. As you can see from the link I posted, some estimate 20, others a bit more. One of TFP's foremost scientists estimated 24-26 drops per ml (post #5), so 25 seems to be a good average.
    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.
    If you enjoyed your TFP experience, please consider donating to Support TFP!

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    Re: FC, High CYA, algae and tri-chlor

    I guess the CYA test is the same usage per test, regardless of CYA level.

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    Mod Squad kimkats's Avatar
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    Re: FC, High CYA, algae and tri-chlor

    You are correct. The neat thing (the only thing I like about this test LOL) is that you can pour it back and forth to help you find the average.

    TFP Moderator 33x52 round AG 25,600 gals Sand Filter 1.5hp Pump - 2 Speed, SLAM, Pool School, Recommended Levels, Recommended Chemicals, Pool Math, Chlorine/CYA Chart, TF-100 Test Kit

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    Re: FC, High CYA, algae and tri-chlor

    OK, guys and girls... It'll cost me $64 to return the 100 pounds of tri-chlor tabs and it seems that Leslie's will refuse to take back the PhosFree ($45) So, my question is: how much will the FC be raised and the CYA be raised in a 22,000 gallon pool by one 3-ounce tab of tri-chlor? I see in the pool calculator that I can raise the FC from 7 to 8 by dissolving 3.2 ounces of tri-chlor, but how much will that raise the CYA?

    Oh, wait! Never mind! I hadn't scrolled low enough! I found the calculation at the bottom.
    Last edited by JamesP; 09-27-2016 at 12:29 PM. Reason: found it!

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    Re: FC, High CYA, algae and tri-chlor

    Perhaps you can trade the PhosFree for something useful...like a new pool rake or a floating toy? And Craigslist might be a solution for the tabs. Tell them about TFP AFTER you get the cash....
    16X32 AB, Pentair SD filter, 3/4hp Pentair Optiflo, CircuPool RJ30+ swg, TF 100

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    Re: FC, High CYA, algae and tri-chlor

    I think their policy is that chemicals can't be returned, not that they won't give money for them, but that they can't reintroduce them into their store. However, I will try. I've already put the tabs on Craigslist. One scammer so far... Yes, I won't mention TFP until AFTER! Thanks!

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