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Thread: Water test results - please advise

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    Water test results - please advise

    Hi,

    I got TF-100 test water kit 2 days ago and started testing the pool water.
    Initially we had low alkalinity (around 40 and low pH 6.9 according to pool store test), so 2 days ago we dumped around 25 lbs of baking soda. pH increased as well as alkalinity.

    Here are the yesterday results:
    TC 1
    CC 2.5
    pH 7.2
    TA 130
    CH 100
    CYA ~100

    It looks like TC is too low. We have chlorinator which was set to 6, now we set it to 7. Should we increase the flow even more?
    CH 100 is OK? We have vinyl pool.

    Thanks for any hints.

    matali
    Vinyl in-ground 26,000 G, sand filter, chlorinator (replaced with bleach), TF-100

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    Richard320's Avatar
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    Re: Water test results - please advise

    Slow down! What kind of chlorinator? Is it a salt water generator, or a puck dispenser?

    Trichlor pucks add chlorine, but they also add CYA, and they also are very acidic and drive pH and TA down. That sounds like your situation. Turning the chlorinator up is only making the situation worse. If CYA is 100 - and it's likely higher than that - you should repeat the CYA test using the dilution method described in Extended Test Kit Directions. Post 8, step 9.

    Let's say your CYA turns out to be exactly 100, just for demonstration. Your minimum FC level should be 8!! The trouble is, if you try to boost FC from 1 to 8 using trichlor pucks, you'll also add another 4 CYA, which means FC needs to be a little higher, which means more trichlor, which means... It's a vicious spiral. So, you need to use something without CYA in it: bleach. http://www.troublefreepool.com/conte...nate-your-pool

    The CH at 100 is fine for a vinyl pool. You can't damage the plaster because you don't have a plaster finish.

    Have you read the ABCs yet? It might help you understand what we write and understand what those test results mean.

    How does the water look?
    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.
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    Re: Water test results - please advise

    read "The ABC's of Pool Water Chemistry" up in Pool School. It helps you understand why we test these parameters.

    1. Your CYA of 100 is too high. 50 is about normal and will require a 50% drain of your pool but will make EVERYTHING else easier.

    Once you get your CYA back to a manageable level, it will be fairly simply to SLAM your Pool (Look in Pool School) Next, continue that SLAM process until your pool sparkles. we'll help you every step of the way.
    Dave S.
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    Re: Water test results - please advise

    Quote Originally Posted by Richard320 View Post
    Slow down! What kind of chlorinator? Is it a salt water generator, or a puck dispenser?
    Puck dispenser (for chlorine tablets bought in the pool store)
    Quote Originally Posted by Richard320 View Post
    Trichlor pucks add chlorine, but they also add CYA, and they also are very acidic and drive pH and TA down. That sounds like your situation. Turning the chlorinator up is only making the situation worse. If CYA is 100 - and it's likely higher than that - you should repeat the CYA test using the dilution method described in Extended Test Kit Directions. Post 8, step 9.

    Let's say your CYA turns out to be exactly 100, just for demonstration. Your minimum FC level should be 8!! The trouble is, if you try to boost FC from 1 to 8 using trichlor pucks, you'll also add another 4 CYA, which means FC needs to be a little higher, which means more trichlor, which means... It's a vicious spiral. So, you need to use something without CYA in it: bleach. http://www.troublefreepool.com/conte...nate-your-pool

    The CH at 100 is fine for a vinyl pool. You can't damage the plaster because you don't have a plaster finish.

    Have you read the ABCs yet? It might help you understand what we write and understand what those test results mean.

    How does the water look?
    The water looks good - crystal blue.

    I am going to do this extended CYA test with diluted water, so I will have correct values.
    Thanks!
    Vinyl in-ground 26,000 G, sand filter, chlorinator (replaced with bleach), TF-100

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    Mod Squad jblizzle's Avatar
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    Re: Water test results - please advise

    Welcome to TFP!!!

    After digesting the ABCs of Water Chemistry that Richard and Dave pointed you to ...

    Please read these as you should soon realize that the tablet feeder is not a long term solution:
    Recommended Pool Chemicals
    How to Chlorinate Your Pool
    Jason, TFP Moderator
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    Re: Water test results - please advise

    Quote Originally Posted by duraleigh View Post
    read "The ABC's of Pool Water Chemistry" up in Pool School. It helps you understand why we test these parameters.

    1. Your CYA of 100 is too high. 50 is about normal and will require a 50% drain of your pool but will make EVERYTHING else easier.

    Once you get your CYA back to a manageable level, it will be fairly simply to SLAM your Pool (Look in Pool School) Next, continue that SLAM process until your pool sparkles. we'll help you every step of the way.
    I know you guys mainly use bleach, but I have full bucket of those chlorine tablets and the chlorinator. If I drain the water and let's say achieve 50 CYA, can I still use it?
    Vinyl in-ground 26,000 G, sand filter, chlorinator (replaced with bleach), TF-100

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    Mod Squad jblizzle's Avatar
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    Re: Water test results - please advise

    Only if you plan on draining again soon ....

    PoolMath will tell you how quickly the CYA will add up from the tablets.

    And the higher the CYA, the higher you need to maintain your FC. See the FC/CYA Chart.
    Jason, TFP Moderator
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    Re: Water test results - please advise

    I think I made a mistake regarding CC value. It is CC=0.5

    I just checked my notes and compared with instructions from TF kit.
    So from K-1000 test for Chlorine (the one with pH) I got the value = 1

    From Chlorine Drop test: I had TC=2.5, as FC=2 and CC=0.5.
    I will retest it tonight, but in case CC=0.5 - does it make any difference in your recommendations?

    I understand that that Chlorine Drop test is more accurate... (I am sorry but all this pool and water testing is very new to me.)
    Vinyl in-ground 26,000 G, sand filter, chlorinator (replaced with bleach), TF-100

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    Re: Water test results - please advise

    Same recommendation. You still need to raise free chlorine above 8 for CYA= 100. http://www.troublefreepool.com/conte...art-slam-shock

    Draining a bunch of water just means you'll have to do a bunch more rebalancing, and if you resume using pucks, in a month or so, you'll be draining again. And if somehow algae gets a start, you'll have to drain a whole lot more top get the CYA down to a manageable number where you can run the SLAM process.

    Draining a bunch now or doing it in stages and watering the lawn with the pool water doesn't matter, as long as you maintain adequate FC for the CYA level. What does matter is stop adding CYA via pucks. They'll last for years, provided you keep the bucket closed. If you drain down to winterize, you can use them next spring to raise CYA at the beginning of the season. Your best bet to maintain that clear water is to maintain the FC using bleach. You'll find your pH and TA need less adjustment that way, too.
    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: Water test results - please advise

    OK, thanks, I think I understand it now better:

    I should stop using pucks to cut CYA level, measure CYA, and then increase FC (using bleach) to be within the range for given CYA.
    If I want to have lower CYA, then I need to drain some water and then balance FC.

    I understand it is better to have lower CYA and lower FC. Is there any other benefit (except cost of putting more chlorine into water)? What is the ideal level of CYA? Is my current leve CYA=100 safe?
    Vinyl in-ground 26,000 G, sand filter, chlorinator (replaced with bleach), TF-100

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    Re: Water test results - please advise

    It is not necessarily "better" to have lower CYA. The high CYA just requires higher FC levels, just as safe, and the real issue is if you need to SLAM the pool with high CYA levels as the FC gets to be very high and require a lot of bleach.

    Where you are I would think 30-40ppm would be plenty for the CYA. You CYA of 100 (ish, is it higher?) can be safe if you maintain high enough FC levels.
    Jason, TFP Moderator
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    Re: Water test results - please advise

    Quote Originally Posted by matali View Post
    OK, thanks, I think I understand it now better:

    I should stop using pucks to cut CYA level, measure CYA, and then increase FC (using bleach) to be within the range for given CYA.
    If I want to have lower CYA, then I need to drain some water and then balance FC.

    I understand it is better to have lower CYA and lower FC. Is there any other benefit (except cost of putting more chlorine into water)? What is the ideal level of CYA? Is my current leve CYA=100 safe?
    Yes.

    As long as the water stays clear and sparkly, there's no real problem from a health standpoint to having high CYA, as long as the FC level is correct. But here's the down sides: 1) Most test kits can't measure the high FC levels you need to maintain. The pool's appetite will be roughly the same, whether CYA is 50 or 100, but it's a daily drop from 10 to 8 instead of 6 to 4. So testing is one problem. You won't be able to just use the quick-check color block test. It will mean a full-on FAS-DPD test every single time. 2) the pH test becomes iffy when FC is above 10 and the reagent starts to react and will make it read higher than it actually is. At 100 CYA, you'll be maintaining 7 to 10, so it's do-able. But what if CYA is actually 120 or 130? Your minimum FC level is then 10, so your pH reading will always be suspect. 3) If you do develop algae, the shock level to kill it becomes so high that just the initial load of bleach to get it to shock level starts to cost as much as the water to refill it. And since you lose a percentage to sunlight, not a fixed amount, raising FC to some astronomical number, say 48 FC, means you lose huge quantities to the sun before it can even start killing algae.

    I've maintained a pool with super high CYA and no opportunity to drain and refill due to water restrictions. I can tell you firsthand, it's a lot easier to maintain things with lower CYA.
    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: Water test results - please advise

    So I will retest the CYA today (with this extended test) to see where we are.

    By the way how easy is to drain the pool? How you discard the water (by watering the plants?). We have well and septic system on the property...
    Vinyl in-ground 26,000 G, sand filter, chlorinator (replaced with bleach), TF-100

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    Re: Water test results - please advise

    Quote Originally Posted by matali View Post
    So I will retest the CYA today (with this extended test) to see where we are.

    By the way how easy is to drain the pool? How you discard the water (by watering the plants?). We have well and septic system on the property...
    In that case, I'd start doing it in steps. Drain off a few inches - whatever the lawn can absorb, and then refill. It will be slow going, but you can't just dump it all down the drain. If you overwhelm the septic tank, things will bypass the baffles and end up clogging the leach lines. You don't want that. Nor do you want to strain your well that badly. So a few inches at a time.

    If you figure out your average depth, you might be surprised. If it's something like four feet average, then the diference between normal depth and bottom of the tile will be something like 3". That's 6%. If your drain is plumbed such that it;s possible to go below the skimmer, 5" would be a 10% reduction in CYA.

    My plumbing is set up with a hose faucet on the return line, so I just connect a hose and drag it out wherever I want to water. If your filter has a "waste" setting, that's even faster. Or if you have a little sump pump sitting around, connect that to a hose and sprinkler and soak the lawn.
    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: Water test results - please advise

    Thanks for all the replies.

    I retested CYA using extended method, it was 120 and pH=7.2, FC=1.5 . We drained maybe 2 inches, refilled the water and dumped one big Clorox jug of 8.25% bleach.
    Retested yesterday - CYA=150, pH=7.5, FC=5.5 (water crystal clear). After that drained 2 inches again and refilled the water. I will retest it today.
    Obviously it looks that my CYA testing is not very reliable yet (hopefully the more I test, the better I get).

    But why pH raised?

    FC got much higher. I assume I should pour even more to compensate for high CYA level. However it is hard for me to pour more bleach because I know that chlorine is a toxic gas (although in water it forms HOCl) and the general recommendation is to have this level between 1 and 3. I have small kids and my daughter always swallow some water, so I am worrying about all of this. Any thoughts?

    Thanks,
    matali
    Vinyl in-ground 26,000 G, sand filter, chlorinator (replaced with bleach), TF-100

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    Mod Squad jblizzle's Avatar
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    Re: Water test results - please advise

    First, why are you only draining 2" at a time? That is likely at best only replacing 5% of the water (and thus lowering the CYA by 5%) at a time and will take forever to get it down.

    What is the pH of the fill water? That could raise the pH of the pool.

    Finally, your FC is no where near high enough to prevent algae. At a CYA of 100ppm, you need a minimum of 7ppm to prevent problems. Likely you should keep it above 8 or 9ppm. See the FC/CYA Chart.

    The 1-3ppm recommendation is based on no CYA in the water ... this is what is always stated because no one seems to understand the FC / CYA relationship. With CYA, the chlorine is much less harsh and not a concern. You can search the forum for the many threads discussing what chlorine level is safe.
    Jason, TFP Moderator
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    Re: Water test results - please advise

    Thanks, jblizzle!
    Regarding the slow drain - I think we are too cautious (pool owners just for 3 weeks). The look of the water is deceiving Will drain more tonight and I will retest pH of my source water to be sure.

    Regarding FC, I started searching other threads and found this written by chemgeek: Free Chlorine (FC) does not measure active chlorine, but rather the chlorine reserve or reservoir that is mostly inactive. which makes sense now.


    By the way I just don't understand how those pool guys can work without knowing of this CYA/FC relation... I assume half (or most) of the pool owners that are using chlorine pucks have this kind of problems.
    Vinyl in-ground 26,000 G, sand filter, chlorinator (replaced with bleach), TF-100

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    Mod Squad jblizzle's Avatar
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    Re: Water test results - please advise

    Sure, they have these problems and go in and spend $100 on the magic cure ... which does not work, so they buy the $100 super-terrific magic pill ... which also does not work. Then the pool store gives up, tells you a line about "chlorine lock" and that you need to replace water so you can start the cycle over. It is in fact a brilliant money making strategy
    Jason, TFP Moderator
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    Re: Water test results - please advise

    Yes, that's so true -the first week I already spent $100 on chelating agent and other stuff and then it turned out we have no metal problem...
    Vinyl in-ground 26,000 G, sand filter, chlorinator (replaced with bleach), TF-100

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