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Thread: CYA test

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    DencoPaul's Avatar
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    CYA test

    Greetings...

    Site has been immense help thus far. Just bought K-2006 test kit and salt test strips from TFTestKits. Yes, was thinking of going with the TF-100 but I have had a K-2005 for years and am used to the testing methods, even though the FC is new with the DPD-FAS. Very good to have that, because my current FC level would have bleached the old K-2005 FC test out. Hooray for good advice!

    I had posted previously about switching to SWG but when I read all about the salt deterioration of natural stone around pool, I held off on making the switch until I had the time to use a high quality sealer on my stone coping. So went ahead and purchased additional cal hypo and still have trichlor tabs that I have been using--that should last me half the summer and I will do something by July/August. A little more time to price shop and watch for sales on the SWG--leaning towards CompuPool 36 for my 22.5K gallon pool.

    Anyway, so I tested everything and here are my numbers:

    FC=18 (just shocked last night after heavy use over weekend and finding dead frog in skimmer last night--used a bit extra just to be on safe side)
    CC=0
    PH=7.7 (adding gallon MA tonight and then aerating to assist in bring down TA)
    TA=150
    CH=280
    CYA=not exactly sure

    OK, I am seriously colorblind, to the point of getting my neighbor to confirm my PH. Usually I guess correct on things but you also start second guessing self too.

    So when I test for CYA, my eyes start to play tricks on me a bit. My question is whether you should add until black disappears into faint gray or until you see no semblance of a black or gray dot any longer. I know this is not because of colorblindness, but it is part of me always second guessing and wondering if my eyes are playing tricks on me. If I go to where I do not see black dot (but light shade of gray), my CYA does not even register, meaning more than 100 and just a guess where it is. If I go to where I think I cannot see black or gray or any shade thereof, it hits right at 100. Both are too high I know and as soon as I am back from vacation, I will cease using trichlor tabs until I get that number where it should be. But while on vacation for week, I would rather keep using the trichlor just to be on safe side--a few extra points will not be that big of deal IMHO vs. algae bloom if we get rain or nutty weather while gone--need pool to be swimmable for pet-sitter. Now hopefully I will be working to bring down off of the 100 and not something like 200 or unknown. As we get to July and August, we get enough evaporation here in North Texas that I will get those numbers down quicker than my water bill will like!!! Plus, when I go to SWG hopefully by the end of summer, I will be glad to have some of the CYA in the pool.

    So, can anyone shed any light on how I should be accurately reading the CYA test.

    Thanks.

    Paul
    21.5K Gallon Inground Plaster Pool (Built 1977/Acquired 1996/Refinished 2002)
    Triton II TR60 Sand Filter (New 2011) WhisperFlo 3/4HP Pump (New 2011)
    Boost-Rite Booster Pump (New 2016) Legend Pressure Side Cleaner (New 2010)

    “To know and not to act is not to know.” - Lao Tse

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    Mod Squad jblizzle's Avatar
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    Re: CYA test

    The dot should be gone. Here is more info on the test with a link to example pictures:
    extended-test-kit-directions-t25081.html#p206397

    Try re-doing the CYA test using a 50/50 mix of pool and tap water, then double the result ... that will allow you to maybe get a better estimate, especially if it is > 100ppm.
    Jason, TFP Moderator
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    Mod Squad Bama Rambler's Avatar
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    Re: CYA test

    You should not see the black dot at all. Like it was never there. Do it in the bright sun with the sun against your back.

    CYA doesn't evaporate so when the water evaporates and you refill it the CYA is exactly where it was. Teh only way to get rid of it is to waste water (backwash or splashout, etc.) or have an R/O treatment performed.

    If it tests at 100 it could be much higher than that. take a sample of pool water and dilute it 50/50 with tap water and do the test again multiplying the result by 2. That'll give you and idea if it's close to 100 or way over.
    Dave J. TFP Moderator
    24' x 52" Round AGP. 2hp/¼hp SPL Power-Flo 2-speed pump. 200sqft Waterway Cartridge Filter. 45MHP2(3GPD) Stenner Peristaltic Pump
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    DencoPaul's Avatar
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    Re: CYA test

    Thanks guys...

    Anyone know what the approximate cost of R/O is--hiring someone to come do it vs. doing it yourself, assuming that you can rent the gear?

    Interesting on the evaporation not clearing CYA. The reason I assumed was that in the past, I might start out the summer at 70 or 80 and by the end of August, it would be down below 50. But I have never started the summer this high. The only thing I can think of is that we have a very mild winter, so I actually used more tabs over the winter than normal--when we get a normal to bad winter, I am putting about 1 tab in the chlorinator a month. This year it was actually around 3. Still, that seems like it should not have gotten over 100.

    I will recheck it using the 50/50 method described.

    Now, my water is crystal clear--yes I realize the chlorine level is high after uber shocking yesterday but if past history is any indication, it will be back down around 5-6ppm by Thursday. So, if my chlorine is working, what is the harm in the high CYA levels in the short term? I want to get it lowered--although going the SWG route in a few months, so not too much lowered--but would rather not empty half the pool doing it.

    For grins, lets just say that it truly is around 100. Would I be OK to knock it down to only 70 or 80 in anticipation of getting SWG? Isn't 60-70 the target for CYA with SWG? As long as my chlorine is working properly and not being inhibited by the high CYA, am I safe to not go some radical route to try and get it down to 40ish?

    Thanks...

    Paul
    21.5K Gallon Inground Plaster Pool (Built 1977/Acquired 1996/Refinished 2002)
    Triton II TR60 Sand Filter (New 2011) WhisperFlo 3/4HP Pump (New 2011)
    Boost-Rite Booster Pump (New 2016) Legend Pressure Side Cleaner (New 2010)

    “To know and not to act is not to know.” - Lao Tse

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    Mod Squad jblizzle's Avatar
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    Re: CYA test

    In Tucson I believe it was $300-$400

    EDIT: And anything below about 90ppm on the CYA is manageable if you do not have to shock. So you could just lower to that range and add bleach until you get a SWG.
    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
    Pool School + Test Kit + PoolMath = A TROUBLE FREE POOL
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  6. Back To Top    #6
    DencoPaul's Avatar
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    Re: CYA test

    Thanks to everyone that posted in response...sorry just getting back but was rushed to go out of town and rushed when back to work. First chance to offer thanks and get some additional opinions.

    Anyway, did the diluted test with half pool water and half tap water for the CYA...came out registering just below 70, meaning I have between 130-140ppm CYA. So while not exacting, if I was to empty half of the pool, I would lower that number to about 70, correct?

    So if I did that and continued to use the trichlor tabs and cal hypo shock for the next two months (to use up my supply of tabs and powder), I would probably keep my CYA under 100 when I switch to salt at the end of July/first of August? I saw in another post that each trichlor tab adds about 1ppm of CYA but I did not see into what quantity of water. My pool is about 22.5K gallons. When I refill my Rainbow with a stack of tabs, it takes 10 and as long as the outside air temperature remains in the low to mid 90s as a high, that stack will last about 2 weeks. So I would be putting in 40-50 trichlor tabs over the next two months. Is that going to add 40-50ppm and put my math to shame or is that 40-50ppm diluted by the number of gallons in the pool in a different calculation?

    One suggestion was to go to liquid chlorine and quit using the tabs. Not opposed to that but I guess I would like to use up the chemicals I have on hand. Also, if using the liquid chlorine, would or could I still also use the cal hypo too? Certainly, if I choose to use up my chemicals on hand and I run out before ready to do the SWG, I will definitely be going the liquid route, especially if I am only able to bring my CYA numbers to 70-100.

    Now, for the water drain. Obviously to dump half my pool water, I will need to use a submersible pump and not just use the drain on the pool valve. I guess I can move the first water out faster with the valve in drain until down to skimmer level and then do the rest with sub-pump. Should I do this 50% dump all at once or, if I really wanted to get the CYA down to proper levels, should I do a 25% dump and fill on four consecutive weekends, where I would realistically turnover about 75% of the water (accounting for remixing new with old). Then I could keep my water level on the low side (just above skimmer level), hope for rain to aid in refilling the pool some, and get my CYA down to 40-50ppm by the end of the month? Obviously that would cost more in water but getting that CYA number as low as I can seems like the best thing.

    Commenting on the Reverse Osmosis suggestion: I really liked that idea because it would be a way to completely clean my water and start over with nothing but pure water. Also, the conservationist in me would like to not just poor 12K gallons of water down the drain. But there seems to be no one in the dallas area that offers this as a service or a rental unit to do it myself. I finally did talk to one very helpful person at an industrial water treatment entity that said three things that made a lot of sense: 1. even with RO, you are going to lose at least 20% of existing water in the process of dumping off the collected waste from the treatment. 2. Unless I brought a holding tank on-site, that 20% would likely be higher, maybe even close to 40%, because running the water through the RO and immediately back into the pool would take doing the RO 3-5X (basically cycling close to 100K of water throught the RO) to account for putting the cleaned water back into the pool and mixing back with unfiltered water. He also said without a holding tank, I would not ever get 100% RO quality water, likely only 85-90%. 3. He understood what I was trying to accomplish but said I was the first person in his 20+ years (all in Dallas area--this is industrial company not just whole house filter dealer) in water treatment business that had ever asked what I was asking about. He said our water rates in this area are just too cheap for it to be a viable service or certainly someone would have already started a business doing RO on pools (BTW, local Leslie's counter-jockey looked at me like I had three heads when I asked if they provided RO service!). He said he could see that in Arizona or California or other similar region with high water rates it might be viable, but not here. A rough calculation of the cost to me for the water replacement will be about $125, so less than the RO rate someone quoted in Arizona--but I still hate dumping 12.5K of water!!!

    So even if I could find someone to do the RO on my pool, if I am going to have to add 30-40% water back in plus the cost of the service or rental unit, I am far better off just dumping half the water from a cost standpoint.

    Sorry, I know I am long winded but just a lot of questions to ask before I tackle this tomorrow AM...thanks for all the help past, present, and future...

    Paul
    21.5K Gallon Inground Plaster Pool (Built 1977/Acquired 1996/Refinished 2002)
    Triton II TR60 Sand Filter (New 2011) WhisperFlo 3/4HP Pump (New 2011)
    Boost-Rite Booster Pump (New 2016) Legend Pressure Side Cleaner (New 2010)

    “To know and not to act is not to know.” - Lao Tse

  7. Back To Top    #7
    Mod Squad Bama Rambler's Avatar
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    Re: CYA test

    Adding 50 trichlor tablets to your pool over the next couple of months will add about 80 ppm CYA. That means that you'll have to drain half your water again to get the CYA down to manageable level again.

    You can certainly use your main drain to drain your pool. You don't need a sump if you can select the main drain alone. Don't stop your pump once you start draining because you may not be able to get it primed again once the level gets so low.
    Dave J. TFP Moderator
    24' x 52" Round AGP. 2hp/¼hp SPL Power-Flo 2-speed pump. 200sqft Waterway Cartridge Filter. 45MHP2(3GPD) Stenner Peristaltic Pump
    Pool School ----- Pool Math ----- TF-Test Kit

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    Mod Squad jblizzle's Avatar
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    Re: CYA test

    Responses in Blue.

    Quote Originally Posted by DencoPaul
    Thanks to everyone that posted in response...sorry just getting back but was rushed to go out of town and rushed when back to work. First chance to offer thanks and get some additional opinions.

    Anyway, did the diluted test with half pool water and half tap water for the CYA...came out registering just below 70, meaning I have between 130-140ppm CYA. So while not exacting, if I was to empty half of the pool, I would lower that number to about 70, correct?

    Correct

    So if I did that and continued to use the trichlor tabs and cal hypo shock for the next two months (to use up my supply of tabs and powder), I would probably keep my CYA under 100 when I switch to salt at the end of July/first of August? I saw in another post that each trichlor tab adds about 1ppm of CYA but I did not see into what quantity of water. My pool is about 22.5K gallons. When I refill my Rainbow with a stack of tabs, it takes 10 and as long as the outside air temperature remains in the low to mid 90s as a high, that stack will last about 2 weeks. So I would be putting in 40-50 trichlor tabs over the next two months. Is that going to add 40-50ppm and put my math to shame or is that 40-50ppm diluted by the number of gallons in the pool in a different calculation?

    Are your tabs 7oz or 8oz? An 8oz tablet will add 1.5ppm to a 22.5k gallon pool. By this plan, you would need to do another 50% drain in a few months to get back down in the 70-80ppm range for a SWG.

    One suggestion was to go to liquid chlorine and quit using the tabs. Not opposed to that but I guess I would like to use up the chemicals I have on hand. Also, if using the liquid chlorine, would or could I still also use the cal hypo too? Certainly, if I choose to use up my chemicals on hand and I run out before ready to do the SWG, I will definitely be going the liquid route, especially if I am only able to bring my CYA numbers to 70-100.

    What is your CH? Cal-hypo will be adding calcium to your pool and if that gets too high it can lead to scaling. Liquid is certainly safer as it does not add the "bad" byproducts.

    Now, for the water drain. Obviously to dump half my pool water, I will need to use a submersible pump and not just use the drain on the pool valve. I guess I can move the first water out faster with the valve in drain until down to skimmer level and then do the rest with sub-pump. Should I do this 50% dump all at once or, if I really wanted to get the CYA down to proper levels, should I do a 25% dump and fill on four consecutive weekends, where I would realistically turnover about 75% of the water (accounting for remixing new with old). Then I could keep my water level on the low side (just above skimmer level), hope for rain to aid in refilling the pool some, and get my CYA down to 40-50ppm by the end of the month? Obviously that would cost more in water but getting that CYA number as low as I can seems like the best thing.

    The more water you change at once, the greater the reduction in CYA. But, there are consideration like what your ground water table is to be sure your pool or liner does not float out of the ground. Another option is putting a plastic sheet over the pool and draining from below and adding above ... this keeps the water from mixing and keeps your pool pretty full during the process.

    Commenting on the Reverse Osmosis suggestion: I really liked that idea because it would be a way to completely clean my water and start over with nothing but pure water. Also, the conservationist in me would like to not just poor 12K gallons of water down the drain. But there seems to be no one in the dallas area that offers this as a service or a rental unit to do it myself. I finally did talk to one very helpful person at an industrial water treatment entity that said three things that made a lot of sense: 1. even with RO, you are going to lose at least 20% of existing water in the process of dumping off the collected waste from the treatment. 2. Unless I brought a holding tank on-site, that 20% would likely be higher, maybe even close to 40%, because running the water through the RO and immediately back into the pool would take doing the RO 3-5X (basically cycling close to 100K of water throught the RO) to account for putting the cleaned water back into the pool and mixing back with unfiltered water. He also said without a holding tank, I would not ever get 100% RO quality water, likely only 85-90%. 3. He understood what I was trying to accomplish but said I was the first person in his 20+ years (all in Dallas area--this is industrial company not just whole house filter dealer) in water treatment business that had ever asked what I was asking about. He said our water rates in this area are just too cheap for it to be a viable service or certainly someone would have already started a business doing RO on pools (BTW, local Leslie's counter-jockey looked at me like I had three heads when I asked if they provided RO service!). He said he could see that in Arizona or California or other similar region with high water rates it might be viable, but not here. A rough calculation of the cost to me for the water replacement will be about $125, so less than the RO rate someone quoted in Arizona--but I still hate dumping 12.5K of water!!!

    So even if I could find someone to do the RO on my pool, if I am going to have to add 30-40% water back in plus the cost of the service or rental unit, I am far better off just dumping half the water from a cost standpoint.

    Sorry, I know I am long winded but just a lot of questions to ask before I tackle this tomorrow AM...thanks for all the help past, present, and future...

    Interesting information. Thanks for sharing. It does seem the the cost effective route is just to drain and refill. You can use the drain water to put all over your grass/trees/shrubs/etc.
    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
    Pool School + Test Kit + PoolMath = A TROUBLE FREE POOL
    If you found TFP helpful and we saved you money ... Become a TFP Supporter!

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