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Thread: My inline chlorinator can't keep up (high CYA)

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    My inline chlorinator can't keep up (high CYA)

    I don't know if it's the sun, the heat or what but my inline rainbow 3" tab chlorinator is turned up all the way (5)
    and every two to three days my FC is at 2 or below. I've been supplementing the chlorinator with
    a bottle of Bleach (1.42gal 6%) every 2-3 days just to keep the green algae away.

    Pool: 30K gal. IG with DE filter running 9hrs a day. current water temp 87 degrees.

    I've had the pool sparkling clear last week, but with a heavy holiday swimmer load,
    I've got a little cloudiness that should clear in a few days or so.

    I'm located in Austin TX so it's been hot, sunny in the mid-90s for most of the past two weeks. I've been adding
    about 2 tablets to the chlorinator about every 3-4 days. Should I be seeing this type of chlorine usage?

    My one area of concern is my CYA is high. After diluting my last test, I got a number of around 180.
    This got me thinking, with a high CYA level, my FC is not as effective, so does this promote algae growth which
    in turn consumes the chlorine at a faster rate? I've read that with a high CYA I'd need about 14ppm FC to be
    effective. So with my FC around 2-6ppm, am I stuck in a rapid chlorine cycle of not effective chlorine which promotes
    algae growth which consumes more chlorine? Does this make sense? The one thing that doesn't support this is the
    fact that I've got a fairly clear pool.

    As soon as the kid's swim lessons are finished in two weeks, I'll probably
    drain the pool and get my CYA under control. Yes I know the 3" tabs add CYA which in turn will lead me to drain/refill
    as opposed to using BBB.

    I'd like to get to the point where I can use the inline chlorinator set on low and supplement with Bleach so that my CYA
    doesn't creep up as fast. I'll admit, having a bucket of 3" tabs is a lot more convenient than reminding my wife to pick
    up bleach at the grocery store weekly. Let alone the storage requirements of bleach bottles.

    So does my high CYA and high chlorine demand theory hold any water?

    Thanks for your help,
    -Tim

    30K gal. IG; DE filter

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    Hi, Tim,

    Welcome to the forum.

    It's no theory...it's a dead fact that high CYA is the source of your chlorine usage and occasionally troublesome pool water. It's only gonna' get worse as long as you continue with the pucks.

    Can you use them just a little? absolutely......but they'll still get you sooner or later.

    If you don't like the inconvenience of bleach (who does) you will be resigned to time to time troubles with pool water and then draining the pool every few years to get rid of the excess CYA.

    There are other methods to chlorinate your pool....an SWG or The Liquidator.

    Pucks caused your problem and they will make your problem worse.
    Dave S. - Forum owner
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Thanks Dave for the quick reply.

    I'm glad that I wasn't too off base with the high CYA and the high chlorine usage. I've previously read in these forums
    about the ineffectiveness of chlorine with high CYA, but I don't recall seeing or "I didn't put the two together" that high CYA will force you to use more chlorine. Maybe that's the reason for my aversion to going totally to bleach. My current bleach usage is large due to my high CYA. Maybe once my CYA is under control, I won't be using so many bleach bottles. Currently I get 3ppm with every 1.42 gallon of Bleach I add. (Costco in Austin, 2pack of 1.42gal. Clorox 6% for $4.89?, this works out to 1ppm for about 80cents)

    Is there some calculator or post or rule of thumb that I can estimate what I should expect for chlorine usage in a properly
    balanced pool? My worst case conditions would be sunny (9 hrs. direct sun) temperature around 85-95 with water in high 80's?

    With my current CYA levels for BBB I'd be adding a bottle of bleach every other day. If this can be reduced once I get my CYA under control maybe going totally to bleach would be more palatable. I really want to switch over to BBB but I'm not
    convinced that I'll be diligent enough to keep up with my levels, whereas the inline feeder allows to be a little lax.
    I know I'm bad!

    I haven't been reading these forums too much recently because with the colder winter/spring weather my pool maintenance
    has been relatively easy. So I'm sure the info you gave has been posted here many times. Thanks again for taking the time to help me out, these forums have helped me become more confident in my pool management and less reliant on the local pool store.

    Regards,
    -Tim

    30K gal. IG; DE filter

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    Dave, I'm surprised to hear you say that high CYA can increase chlorine usage. In fact I've heard quite the opposite. It's been stated on this board several times how increasing your CYA DECREASES your chlorine usage. For SWCG users specifically, many were able to decrease their run % (generate less chlorine) and maintain the same FC by increasing their CYA level to 70ish.

    The only way that I could see this being true is if you have an algae or other organic situation in your pool that is constantly destroying your FC yet the FC isn't high enough to kill it due to high CYA. I'd think any pool like that would be VERY green, VERY quickly.

    If you're able to shock your pool (which would need a VERY high FC level due to your CYA) then perhaps it'll kill a persistant organic problem you're having and your chlorine usage might stabilize. It would be short lived however since your chlorine is almost completely ineffective at that CYA level and you'll likely get new algae or organics very quickly.

    Your very next step in maintaining your pool should be to drain at LEAST half of your water and re-fill to get that CYA back under control.
    My Pool:
    12K gal IG gunite with 7' raised spa, gunite waterfall, PebbleTec Caribbean Blue finish, solar heating & in-floor cleaning system

    Equipment: Sta-Rite 300' Cartridge Filter, Intellichlor IC20 SWCG, Sta-Rite 400k BTU heater, Intelliflow 4x160 main pump & Sta-Rite 3/4 hp waterfall pump, EasyTouch controlls w/ wireless controller, TF-100 Test Kit w/ salt test.

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    Tim,

    Anecdotally, chlorine consumption seems to average 2ppm daily. being a little further South than average, 2.5 or so might be closer for your pool.

    Search "liquidator" on this forum. I'm prejudice, but it might suit you to a "T". I have reason to believe (notice I'm not yet promising this) the The LQ allows you to run your pool at somewhat lower FC levels so it may even save a little money on chlorine....not much and don't buy it for that reason......look at it for the convenience.
    Dave S. - Forum owner
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    JasonLion's Avatar
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    At high CYA levels it is possible for the FC level to be low enough that it can't really kill off the algae, but high enough that the algae never really gets fully going, so the pool does not turn green. The result is an apprently clear pool with much higher than normal chlorine consumption.
    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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    Jason,

    That's exactly the question I was trying to figure out if that was plausible.

    "At high CYA levels it is possible for the FC level to be low enough that it can't really kill off the algae, but high enough that the algae never really gets fully going, so the pool does not turn green. The result is an apparently clear pool with much higher than normal chlorine consumption."

    The original reason for the question is that I have a hard time believing that the inline chlorinator if used on it's own is not sufficient to handle the current chlorine demand. If I remember correctly, a couple of summers ago when we moved to this house, I was able to turn the Rainbow flow to half-way open (3-3.5) and was able to take care of the chlorine. Now I have it all the way open and must supplement with bleach. So my original question is, is the reason for this difference from two years ago to today due to the high CYA? I hope so.

    So "rule of thumb" 2-2.5 ppm usage per day would run me about 6 bottles of bleach a week. That's a lot of grocery runs.
    And that's even if the high CYA has no effect on my chlorine usage. Am I missing something here? Do you guys go
    through that much bleach? Maybe it's a factor of treating 30K gallons is the reason for so much bleach.

    I think my best course of action is to get the CYA under control by draining and then see how things settle out. I guess I was trying to get ahead of myself and see if my high setting on the Rainbow chlorinator was due to the high CYA. and once the CYA was back within range, my chlorine usage would go down. But maybe not if I use 2-2.5 ppm / day.

    Thanks again,
    -Tim

    30K gal. IG; DE filter

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    Tim, I'm just up the road from you, in Gtown. I keep my pool sparkling like bottled water with one 96 ounce bottle of bleach from Walmart every evening.

    When we first bought this house it was almost impossible to keep the walls from turning green. I had the tab feeder wide open, tabs in the skimmer and was dumping in dichlor granules every week. THEN I learned about CYA... It was sky high from the previous owners and myself using pool store chems. I went overboard with mine, draining the pool, washing the walls with bleach and then pressure washing the entire pool before I refilled it, but the water is awesome now! It took 20 boxes of borax to get my borates up to 50 ppm, but I don't go to the pool store any longer. Walmart has bleach (I buy many bottles at a time) and Home Depot has muriatic acid for the same price as the pool store.

    Your first action should be to get your CYA down. WAY down from where it currently is. This alone will make it much easier to keep your pool looking great.
    26,000 Gallon Gunnite IGP
    2 HP Challenger High Head Pump
    60sf Nautilus DE filter
    Polaris 280

  9. Back To Top    #9
    Mod Squad JohnT's Avatar
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    Quote Originally Posted by timell
    I think my best course of action is to get the CYA under control by draining and then see how things settle out. I guess I was trying to get ahead of myself and see if my high setting on the Rainbow chlorinator was due to the high CYA. and once the CYA was back within range, my chlorine usage would go down. But maybe not if I use 2-2.5 ppm / day.
    As a point of reference, my ~20,000 gallon pool with normal chlorine demand consumes enough pucks to add 7.5ppm to my CYA level in a week. I had my son-in-law monitor and adjust chlorine levels during a two-week vacation a couple of years ago, so that's keeping a reasonable chlorine level. 7.5ppm per week would get you into trouble quickly.
    TFP Moderator
    20K Gallon 20X36 Vinyl Inground
    Hayward S244T Sand Filter with 1HP Whisperflo Pump. Liquidator C-201 and Solar Heat

  10. Back To Top    #10

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    Quote Originally Posted by HarryH3
    Tim, I'm just up the road from you, in Gtown. I keep my pool sparkling like bottled water with one 96 ounce bottle of bleach from Walmart every evening.
    Harry - do you pour it into a running skimmer?
    35k gal in-ground with spill over spa. 2hp shared pump. Polaris w/ booster. DE filter.

  11. Back To Top    #11

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    Quote Originally Posted by BoilerHorn
    Quote Originally Posted by HarryH3
    Tim, I'm just up the road from you, in Gtown. I keep my pool sparkling like bottled water with one 96 ounce bottle of bleach from Walmart every evening.
    Harry - do you pour it into a running skimmer?
    No, I don't like to have high chlorine levels going directly into the pump and filter. I just pour it into the pool, about 1/4 of the bottle in front of each of my 4 return jets. My pump runs until 9:30 and I try to add the bleach between 8 and 8:30. This mixes the bleach into the water nicely before the pump shuts down for the night.
    26,000 Gallon Gunnite IGP
    2 HP Challenger High Head Pump
    60sf Nautilus DE filter
    Polaris 280

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