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Thread: removing water to lower cya

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    removing water to lower cya

    My CYA is about 95 now and I need to remove water from the pool. Obviously you can only remove so much and then you are below skimmer. Am I correct in thinking that I just need to vacuum to waste to remove the rest. How much would I need to remove to get my CYA in line and do I just leave the vacuum hose in the bottom of the pool until I reach that level?
    18 ft.52" Round Atrium AG -7600 gallons, Sand Filter, Vinyl liner, Royal Entrance Steps, 80 lbs.solarsalt

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    frustratedpoolmom's Avatar
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    In May, I did two partial drains/refills to lower my CYA from over 110 to 70.... I lowered the water to below the skimmer and refilled....I repeated two days later. I could have done it a third time to bring it down but water here is very expensive. I would guess from my own experience and gallonage that would be all it would take for your size pool. Try it once or twice and retest. You don't want to go too low all at once or your pool could collapse. And don't trust the strips, they say my CYA is 30-50, but my drop test says 70.
    Helpful links: Pool School; CYA/Chlorine Chart
    24' round AG pool, 52" high, Raypak heater; Waterway 2 spd Pump;
    150 Sq ft. Clearwater Cartridge Filter; Former and DISSATISFIED "Pool Frog" owner
    http://www.PerfectlyClearPoolService.com

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    Thanks, I guess that is what I am wondering - how low can I go without problems? Can I empty half the pool, a third????Help!
    18 ft.52" Round Atrium AG -7600 gallons, Sand Filter, Vinyl liner, Royal Entrance Steps, 80 lbs.solarsalt

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    JasonLion's Avatar
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    Lowering the water level down to one foot of water in the shallow end is generally safe (unless you have a very high water table), but there is no real need to do that. You can fill at the same time you are draining, leaving the water level reasonably stable. This takes a little more water, but is very reasonable at say a 50% dilution, it also goes more quickly. If you are trying for a 70% or more dilution this becomes pretty inefficent, but the alternatives have issues also.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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    Thanks. So basically I can be taking water out below skimmer level with the vacuum head on the bottom of the pool and set to waste and add water from the top with the hose as usual.

    This is one time when I wish pool stores could sell you something to pour in and dilute all that CYA! Whoever develops that one will have pots of money for bleach
    18 ft.52" Round Atrium AG -7600 gallons, Sand Filter, Vinyl liner, Royal Entrance Steps, 80 lbs.solarsalt

  6. Back To Top    #6
    I wouldn't go much beyond a half a pool, however, you don't need to remove that much, you only need to replace about 1/3rd of your water, that should get you down to 60 ppm

    Oh, as for removal - it's on it's way already
    http://www.yedarnd.com/opportunities/?o ... =1&id=1388

  7. Back To Top    #7
    Waterbug has an AGP!!! Some of the advice given is for inground.

    8000 gallon 20' x 48" round vinyl frame pool, 12" sand filter (don't have the specs on the pump), TF100 test kit
    Handy Links: PoolMath, TF-100 Test Kit, Pool School, CYA-Chlorine Chart
    "Shock" is a process, not a product!

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    That doesn't change much, does it?

    Dilluting water is dilluting water after all.

  9. Back To Top    #9
    Well, the water table is a non-issue, but they might need to be concerned about the liner shrinking and/or the walls collapsing.

    As far as the actual dilution, no difference! 8)

    8000 gallon 20' x 48" round vinyl frame pool, 12" sand filter (don't have the specs on the pump), TF100 test kit
    Handy Links: PoolMath, TF-100 Test Kit, Pool School, CYA-Chlorine Chart
    "Shock" is a process, not a product!

  10. Back To Top    #10
    I figured the liner shrinking wouldn't be an issue if they left 1' in the shallow end as recommended, especially since they were gonna fill it right back up, nor would they need to remove that much water just to lower their CYA into the recommended range

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    You may very well be right... My vast experience has all been with softsided pools... ONLY liner, so shrinkage was not an issue, and no wall, so no worry about collapse.

    (ok, ask dd and dh about the time I fell halfway out of our donut, got stuck on the side, and drained half the pool! )

    8000 gallon 20' x 48" round vinyl frame pool, 12" sand filter (don't have the specs on the pump), TF100 test kit
    Handy Links: PoolMath, TF-100 Test Kit, Pool School, CYA-Chlorine Chart
    "Shock" is a process, not a product!

  12. Back To Top    #12
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    Quote Originally Posted by waterbug
    This is one time when I wish pool stores could sell you something to pour in and dilute all that CYA! Whoever develops that one will have pots of money for bleach
    There are already products on the market. Ace Hardware sells one under it's O-Ace-Sis brand and I believe that Intheswim sells one. I spoke to the president of the company that developed it originally and he told me it was propriatary and NOT melamine when I questioned him about it a while back (melamine is the reagent that we use to test CYA that makes it precipitate out), but then I spoke to the president of the company that manufactures the O-Ace-Sis products recently and he told me that he worked on it with the first man (it was his idea) and they made improvements to it and that it WAS basically melamine along with some type of propriatary clairier or floc. He said that there are about 6 different ingredeints in it. (I believe him since he knew the name of the first man and I never said it to him, just his company's name.) He said one gallon will remove about 20-30 ppm CYA from 10000 gallons it's useful if your CYA is only slighly high but if your CYA is really high draining and refilling is a more cost effect and less troublesome option. It's not exactly cheap either. It goes for anywhere from about $40-$60 a gallon depending on where you buy it.

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    frustratedpoolmom's Avatar
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    diluting CYA

    Quote Originally Posted by waterbear
    Quote Originally Posted by waterbug
    This is one time when I wish pool stores could sell you something to pour in and dilute all that CYA! Whoever develops that one will have pots of money for bleach
    There are already products on the market. Ace Hardware sells one under it's O-Ace-Sis brand and I believe that Intheswim sells one. I spoke to the president of the company that developed it originally and he told me it was propriatary and NOT melamine when I questioned him about it a while back (melamine is the reagent that we use to test CYA that makes it precipitate out), but then I spoke to the president of the company that manufactures the O-Ace-Sis products recently and he told me that he worked on it with the first man (it was his idea) and they made improvements to it and that it WAS basically melamine along with some type of propriatary clairier or floc. He said that there are about 6 different ingredeints in it. (I believe him since he knew the name of the first man and I never said it to him, just his company's name.) He said one gallon will remove about 20-30 ppm CYA from 10000 gallons it's useful if your CYA is only slighly high but if your CYA is really high draining and refilling is a more cost effect and less troublesome option. It's not exactly cheap either. It goes for anywhere from about $40-$60 a gallon depending on where you buy it.
    Waterbear,

    How does it work? Do you think it's worth a try....my CYA is about 70, I haven't had any problems since the end of May so maybe I should just count my blessings and be thankful for this forums members' excellent advice, BBB is working great, so I should just enjoy my pool? Or should I give it a try?
    Helpful links: Pool School; CYA/Chlorine Chart
    24' round AG pool, 52" high, Raypak heater; Waterway 2 spd Pump;
    150 Sq ft. Clearwater Cartridge Filter; Former and DISSATISFIED "Pool Frog" owner
    http://www.PerfectlyClearPoolService.com

  14. Back To Top    #14
    In a price comparison, if my pool was 20-30 ppm higher that it should be (say at 90ppm), i'd want to dump 1/3 of my pool water - pool being 30 feet, it's about 24000 gal, I'd have to dump 8000 gal. at $110/4000gal for water, it'll cost me $220.
    at the high price of 60/gal for the remover (and it would be that in Canada), I'd need about 2.4 gal, but I have to buy 3 for $180.
    If the shelf life of an opened bottle sucks it's waste, if it lasts, I'll have some for a small adjustment down the road.
    From a practicality standpoint, It's probably easier to use teh remover although it sounds like you'd have to vac to get the solids out.
    I'd feel better doing a dump and fill because I'm not dumping chemicals into my pool and don't have to vac to waste losing more water!

  15. Back To Top    #15
    JasonLion's Avatar
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    I have not seen any reports of someone actually trying the CYA remover. I have been wondering how neatly it works, does the pool become a cloudy mess that takes days to clear or does it all settle and a single vacuuming takes care of it?

    frustratedpoolmom - I wouldn't worry about CYA at 70. Many people run CYA at 60-90 to cut down on chlorine usage.

    matt4x4 - my water cost is far lower, so it is much cheaper for me to simply replace water. Plus, many of the people who need to reduce CYA are trying to come down from 150 or 200 or even 300, at which point you would need far more CYA remover and replacing water becomes more attractive even at your water costs.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

  16. Back To Top    #16
    Jason - just an FYI - I know you likely know this, but you stated 60-90, and anything over 80 is a real detriment to chlorine effectiveness, even though your chlorine dissipates more at 30-40 of CYA, you don't have to run more than 1-2ppm chlorine where once you're up above 80 you'll be needing 3-4ppm (effectively double) just to keep it at a safe level.

  17. Back To Top    #17
    matt, are the levels you mentioned referring to SWG?

    Based on chem geeks FC target of 11.5% of CYA ppm, I get-

    30 ppm CYA- 3.45 ppm FC
    40 ppm CYA- 4.6 ppm FC
    80 ppm CYA- 9.2 ppm FC

    Each having the same effective killing power, but the higher FC in the higher CYA having more staying power in the pool from sunlight degradation?

  18. Back To Top    #18
    JasonLion's Avatar
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    Quote Originally Posted by matt4x4
    Jason - just an FYI - I know you likely know this, but you stated 60-90, and anything over 80 is a real detriment to chlorine effectiveness, even though your chlorine dissipates more at 30-40 of CYA, you don't have to run more than 1-2ppm chlorine where once you're up above 80 you'll be needing 3-4ppm (effectively double) just to keep it at a safe level.
    I don't believe there is any great difference between 80 and 90. If you are willing to go to 60-80, then how different is 60-90? Obviously there is a huge difference between 30-50 and 60-90, but if you are willing to go up to 80 then why not 90? Of course you need to increase FC levels as your CYA goes up to compensate, but that continues working even with very very high CYA levels.

    There is strong anecdotal evidence that higher CYA levels reduce total chlorine consumption, contrary to the long promoted diminishing returns rule. I am currently assuming that protection continues to improve at still higher CYA levels. This is the motivation for exploring higher levels. Unfortunately very little solid evidence is available, but the anecdotal evidence seems consistent with what little real testing has been done.

    Some public pool laws only allow CYA levels up to 80, others allow up to 100, others don't specify. Most of them seem to be based on not understanding the CYA chlorine relationship and having problems with too little chlorine for the higher CYA levels. They appear to have decided that limiting CYA is the only available choice since most don't appear to consider anything but fixed FC requirements.

    From my point of view the upper limit is mostly one of reliable testing. Most of the tests only test up to 100. Setting a target below 100 allows you to reliably tell when you have gone too high. Likewise we don't normally recommend CYA levels below 30 more because of testing considerations than anything else.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

  19. Back To Top    #19
    80 as far as I'm aware was always preached as the UPPER LIMIT, once you start stretching the upper limit, you run into problems - so if you do land at 80, you should seriously think about a drain/replace to lower that level, if you start to run at 90 before doing a drain and replace, then next thing you know, people push it to 100, 110, and all of a sudden, its a LOONG way off the original set max of 80.
    I try to stick between 40 and 60 which is a long way from 80 and a longer way from 90, once I hit 60, I pray for rain, if rain is to come tomorrow, I backwash today.

  20. Back To Top    #20
    JasonLion's Avatar
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    It is worth having some respect for things that are "always preached". Those bits of information often have all kinds of unstated reasoning and hard won experience behind them. But that doesn't mean that they are always right. Nearly everyone in the industry explains how to lower TA incorrectly and things that are commonly preached elsewhere about calcium levels for vinyl liners are both all over the place and generally wrong.

    I believe in being practical. Tell me what goes wrong when CYA is recommended at 60-90 and I will happily change my recommendation. I don't know all of the possible issues that might come up. But I have studied quite a few of them, hopefully all of the major ones. I think I have a fairly good idea of where the 60-80 recommendation came from and why extending it to 60-90 makes sense. Still I might have missed something. I am always excited to come across some reasoning that I haven't seen before so I can try to puzzle it out and broaden my understanding.

    Higher CYA levels have their problems, but for people with constant bright sunlight working through those problems can be easily justified by the chlorine savings. Many pools are fine with 30-50, but there are times when it is well worth it to go higher. I can explain to those people why 100 or higher is not a good idea, but I can't come up with anything that will go wrong at 90 in any way significantly different from what happens at 80, which I know is manageable.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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