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Thread: In line chlorinator and cya level

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    In line chlorinator and cya level

    I am considering installing an inline chlorinator, I realize after reading several post here that it will raise the cya level. My main question is will it raise it so much in 4 months to be a major concern ? In my area pools are only open from Memorial day to Labor day. We typically drain about 1/3 - 1/2 the pool for the winter and have to bring in any equipment that will freeze and crack over the winter. If an inline would be suitable which one works the best, the cl 200 0r the pentair 320 or I have seen some off brands on e-bay for under $60? Thanks
    16,000 gal
    above ground
    sand filter 1 1/2 hp pump

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    Re: In line chlorinator and cya level

    My main question is will it raise it so much in 4 months to be a major concern ?
    Oh yeah, it certainly can. They're fine to use if you monitor your CYA and stop using it when your CYA level gets to 40ppm or so. I have no opinion on a good one....i use just LQ
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
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    Re: In line chlorinator and cya level

    For every 10 ppm Free Chlorine (FC) added by Trichlor, it also increases Cyanuric Acid (CYA) by 6 ppm. So with a typical 2 ppm FC per day chlorine usage, Trichlor would increase CYA by over 35 ppm PER MONTH if there were no water dilution. You have a sand filter so backwashing will help a little and you might have a lower daily chlorine demand, but over 4 months the CYA will likely go up by at least 70 ppm if not 100 ppm or more.

    If you really want to go this route, then you can pay more for supplemental algaecides such as adding PolyQuat 60 weekly. If you have a 3 ppm FC target, then that combination will probably hold you through the season. However, you'll have to drain/refill to start over for the next season unless you are lucky enough to have the CYA drop over the winter. Doing a half-drain/refill will probably not be enough though you can certainly test your levels to be sure.
    16,000 gallon outdoor in-ground 16'x32' plaster pool; Pentair Intelliflo VF pump; Pentair IntelliTouch i9+3s control system; Jandy CL-340 square foot cartridge filter
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    Re: In line chlorinator and cya level

    This might sound stupid but how did I get away with just adding pucks to my skimmer all these years? My father inlaw has been doing it for 25 years and if he didn't have a problem with the liner wrinkling up we would have never thought twice about it, and all either one of us has ever checked is the chlorine level and the ph, and both pools have always been perfectly clear. If trichlor tabs are so bad why does every pool store have enough to fill a garage?
    16,000 gal
    above ground
    sand filter 1 1/2 hp pump

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    JasonLion's Avatar
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    Re: In line chlorinator and cya level

    Using trichlor works great, until it doesn't work at all. For some people the doesn't work at all happens quickly, for others it might be many years. Much of that depends on the length of your pool season and how much water replacement you typically do per year. Short pool seasons with lots of water replacement help trichlor work.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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    Re: In line chlorinator and cya level

    It is not a certainty that a pool high in CYA will get algae because it also depends on whether there are sufficient algae nutrients in the pool water. Also, people with smaller pools and sand filters get more water dilution from backwashing and some areas have summer rains that overflow the pool to dilute the water and some people have short swim seasons and lose some or all of their CYA over the winter. Also, some people use algaecides or phosphate removers that let one get away with higher CYA levels. Also, many people shock their pools weekly which helps make up for too low an FC/CYA ratio during the week.

    In my own pool years ago, I used Trichlor pucks in a floating feeder with a 3 ppm FC target and used algaecide every other week. I had no problem the first year, but I had a mostly opaque pool cover so had low chlorine usage of 0.7 ppm FC per day and a 7-month swim season. I didn't have any summer rains and I had a pool cover pump that put any winter rains into the sewer and I had an oversized cartridge filter that only needed cleaning once a year. So I had very little water dilution. Halfway during the second season, I had trouble maintaining the chlorine level and used more pucks to compensate, but the water still started to turn dull and then cloudy -- an impending algae bloom. Though I started out with 30 ppm CYA, I had 150 ppm CYA after 10-11 months of swim seasons -- 30 + 0.7*30*10.5*0.61 = 165 ppm (so there was some loss from splash-out/carry-out/oxidation of CYA).

    As for pool stores selling Trichlor, they also have many pool owners come in with algae problems and are also sold algaecides, phosphate removers, clarifiers, flocculants at much higher profit margins (especially for the manufacturers) than the chlorine. This is what makes it a multi-billion dollar business. A large number of people coming to this forum have algae problems and the vast majority of them are due to high CYA from continued use of stabilized chlorine products.

    So you may very well not have any problems just using Trichlor, but remember what Clint Eastwood said in Dirty Harry -- "you’ve got to ask yourself one question: 'Do I feel lucky?'" You could certainly try using Trichlor and see how your CYA goes over time. Maybe you've got enough dilution to keep it in check or can increase the FC as it climbs. The key is that you'll know enough to test for it and know how to deal with any problems if they occur.
    16,000 gallon outdoor in-ground 16'x32' plaster pool; Pentair Intelliflo VF pump; Pentair IntelliTouch i9+3s control system; Jandy CL-340 square foot cartridge filter
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    Re: In line chlorinator and cya level

    Quote Originally Posted by duraleigh
    My main question is will it raise it so much in 4 months to be a major concern ?
    Oh yeah, it certainly can. They're fine to use if you monitor your CYA and stop using it when your CYA level gets to 40ppm or so. I have no opinion on a good one....i use just LQ
    I will ditto that 'oh yeah, it certainly can'. It's called everything is fine until mid season or late season and towards the end you think 'I can't wait to close this thing because I can't clear it up and I'm sick to death of shocking every 6 days'...7 years I dealt with this cycle. The 8th..I saw the light. Liquid Chlorine is the way to go.
    Backyard pool-less, but used to be.....
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    Re: In line chlorinator and cya level

    Quote Originally Posted by Jamm999
    This might sound stupid but how did I get away with just adding pucks to my skimmer all these years? My father inlaw has been doing it for 25 years and if he didn't have a problem with the liner wrinkling up we would have never thought twice about it, and all either one of us has ever checked is the chlorine level and the ph, and both pools have always been perfectly clear. If trichlor tabs are so bad why does every pool store have enough to fill a garage?
    $$$$$
    Buy these pucks. Buckets of 'em. And then shock weekly. Buy this packet. A case of 'em.

    A restaurant doesn't stay in business because the food's good. It's the drinks that make the money. Get the razor free...replace the blades. Same concept.
    Backyard pool-less, but used to be.....
    16,100 gallon, 18x38 3.5 ft deep oval AG, Vinyl, Sand, 1hp pump
    http://www.poolservicestech.com Liquidator
    http://www.poolcalculator.com/
    http://www.tftestkits.net TFT100 test kit

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    Re: In line chlorinator and cya level

    I used tablets in a floater last year. My CYA started out at 20 and ended up at 50 by the end of the summer. It was a more expensive route than usual for me as the tablets were more expensive and I needed Borax for my ph. It was an experiment for me. I was more paranoid - testing more than I typically did with BBB. As long as you understand what they do to your pool and how to make the appropriate adjustments, IF NECESSARY, they can be used. YMMV, not all pools will become overstabilized and no two pools are the same.

    Now, having used three methods of chlorination, for me, BBB is the easiest and least expensive, least time consuming, least worrisome form of sanitizing my pool. But that's just me.
    Helpful links: Pool School; CYA/Chlorine Chart
    24' round AG pool, 52" high, Raypak heater; Waterway 2 spd Pump;
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    Re: In line chlorinator and cya level

    A weekly backwash and vacuuming to waste on a regular basis just about keeps the Trichlor added CYA in check (at least it did for me over a 2 year period). Changing to a robot cleaner meant less backwashing and no more vacuuming to waste and CYA quickly climbed to over 100. At that level it is very hard to dilute (2 weeks of reducing levels to bottom of the skimmer and refilling). As I work away a lot I have installed a chlorine pump based on an ORP probe. Once the ORP set point is established it works like a dream. Not maintainence free but its a godsend when you cant do a daily manual dose. Liquid chlorine is definately the way to go, however it is delivered.
    32x16 -16,500 gallon plaster pool with connected spa and spillover, Hayward RS 1 HP pump, 2 Hayward Cartridge filters. 10 hours of direct sun a day and a first time pool owner!!

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    Re: In line chlorinator and cya level

    Ok I'm pretty convinced to get a pump system, A couple of questions. Without knowing my chlorine usage what size pump should I go with? I have seen a couple mentioned here, stenner, peristaltic, etc. I am sort of familiar with a pulsafeeder since I have one on my well system, I believe it's a diaphram pump, it has check valves and an injector, would that type of pump be as effective? I know I would have to have a smaller one since it is a 30 gpd pump. The other very important question is what about protecting the pump from the weather? My equipment is outside mostly under the deck but it is exposed to any rain we get (and this year is alot) Do I have to make sure it is protected from the weather or can it be out like the pool pump motor? Lastly where is the cheapest place to get one? I was considering the liquidator but none of the pool stores around here have them and I wasn't sure if they can be used if placed below on the ground at the same level as the pool ? One more thing I forgot to ask, is it better to have a pump mounted on the tank or remotely ?
    16,000 gal
    above ground
    sand filter 1 1/2 hp pump

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    Re: In line chlorinator and cya level

    All I know is when we used the pucks, every year mid-season (right before the big pool party of course) The pool would get cloudy, and almost nothing would help clear it. Somehow we would always limp along until the end of the pool season, while of course dumping gallons of expensive pool store products into the pool.
    I have a strong feeling that CYA the issue. Hopefully, we won't have that problem this year.

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    JasonLion's Avatar
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    Re: In line chlorinator and cya level

    Stenner dosing pumps have the best reliability record, though several other brands will work just fine. Many such pumps are fine being left outdoors, but not all. Even outdoor rated pumps tend to last longer if they are shaded and protected from rain, but that is not required.
    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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    Mod Squad Bama Rambler's Avatar
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    Re: In line chlorinator and cya level

    Quote Originally Posted by Jamm999
    Without knowing my chlorine usage what size pump should I go with?
    Figure that you will lose about 2-4 ppm fc per day. Worse case, that's a gallon per day of 6%. If you ran your pump 24 hours per day you'd need a 1gpd pump minimum. If you run your pump 8 hours a day then you'll need a 3gpd minimum. Let us know how you run your pump and we can help figure out what size you need. Of course you can always buy a bigger one and run it on a timer for a short time. They're also adjustable so you can adjust the output too.

    Quote Originally Posted by Jamm999
    I have seen a couple mentioned here, stenner, peristaltic, etc. I am sort of familiar with a pulsafeeder since I have one on my well system, I believe it's a diaphram pump, it has check valves and an injector, would that type of pump be as effective? I know I would have to have a smaller one since it is a 30 gpd pump.
    Yes, it would work fine. If you already have a spare one that you could use, you could just run it on a timer for a few minutes while the main pump is running.

    Quote Originally Posted by Jamm999
    The other very important question is what about protecting the pump from the weather? My equipment is outside mostly under the deck but it is exposed to any rain we get (and this year is alot) Do I have to make sure it is protected from the weather or can it be out like the pool pump motor?
    The Stenners have a rain guard as an option and if you use that it can be left out.

    Quote Originally Posted by Jamm999
    Lastly where is the cheapest place to get one?
    Mine came from USWatersystems. It was the cheapest place I found.

    Quote Originally Posted by Jamm999
    I was considering the liquidator but none of the pool stores around here have them and I wasn't sure if they can be used if placed below on the ground at the same level as the pool?
    The liquidator works fine placed on the ground below the waterline. And it would work for your size pool. You may have to make allocations if your suction head is real low but that can be fixed.

    Quote Originally Posted by Jamm999
    One more thing I forgot to ask, is it better to have a pump mounted on the tank or remotely?
    Either way is fine. I have mine mounted on a wall above the tank but on the tank is fine too.
    Dave J. TFP Moderator
    24' x 52" Round AGP. 2hp/hp SPL Power-Flo 2-speed pump. 200sqft Waterway Cartridge Filter. 45MHP2(3GPD) Stenner Peristaltic Pump
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    Re: In line chlorinator and cya level

    Mine is a peristaltic pump. Has worked flawlessly for 18 months other than changing out the length of pipe in the pump which tends to harden. My system also pumps acid so once the setpoint is sorted it keeps CL and PH.
    32x16 -16,500 gallon plaster pool with connected spa and spillover, Hayward RS 1 HP pump, 2 Hayward Cartridge filters. 10 hours of direct sun a day and a first time pool owner!!

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    Re: In line chlorinator and cya level

    I have my pump on a timer to run six to eight hours per day. I would connect a second 110 outlet so the chlorine pump would run whenever the pool pump is on. Should I install a check valve in the 1 1/2 filter outlet before the injection point to keep any chlorine from backing up in the system and backfeeding toward the center drain and ruining another liner? I was told by the pool manufacturer the pucks in the skimmer backfed to the center drain and caused the liner to wrinkle and get brittle. How close to the return should the injector be put ( I'm assuming it uses an injector of some type) Thanks for all the help
    16,000 gal
    above ground
    sand filter 1 1/2 hp pump

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    Mod Squad Bama Rambler's Avatar
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    Re: In line chlorinator and cya level

    Figuring a 6 hour a day run time you need a 4 gpd pump. Since they don't make a 4 gpd, the smallest you could go with would be a 5 gpd. Since you shouldn't lose 4 ppm a 5gpd adjustable pump would be fine. If you wanted a little more leeway you could go with an adjustable 10 gpd pump.
    We had one guy that was going to buy a large pump and inject the chlorine over a few minutes time, and you could do that too, but it would require an additional timer.

    I sized mine so that I could run it on the same timer for the same time as the main pump, and don't have to worry about the sync of the two timers getting off.

    Like I said, if you already have a spare injection pump, the least expensive solution would be to use it and add a timer to run it.

    Don't worry about the chlorine injection harming the liner.
    First, you're only going to be injecting it when the main pump is running and it can't flow backward to the MD.
    Second, it's such a tiny amount you're putting in there it's not going to change the FC of the water enough to harm the liner.
    Third, The pH of liquid is higher than that of the tablets so it's not nearly as much danger to the liner as the acidic tablets are.

    Trichlor is acidic and leaving it in the skimmer when the pump is off lets it dissolve and create a pocket of low pH water that could possibly drift to the main drain because the concentrated pocket of water would be heavier than the surrounding water and would therefore sink. I'm not sure that's what happened to your liner but it's possible even if it isn't likely.
    Dave J. TFP Moderator
    24' x 52" Round AGP. 2hp/hp SPL Power-Flo 2-speed pump. 200sqft Waterway Cartridge Filter. 45MHP2(3GPD) Stenner Peristaltic Pump
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