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Thread: Organic Contaminants

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    Organic Contaminants

    Curious as to the definition of organic contaminants. I had a problem with my old plaster and yellow algae, we'd shock the pool, it would clear, then be back. I think our problem was high CYA since it had been 15 years since the pool was partially drained, but that's just a guess because I entrusted my pool with a pool service.

    All that being said, the pool guy said the reason I had yellow algae was because I had a couple of flowering plants close to the pool water.

    Now that I'm starting with brand new plaster, I want to know if flowering plants would be considered an organic contaminant.

    Thank you kindly for your time!
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    Richard320's Avatar
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    Re: Organic Contaminants

    Yes. Organics are all those things that blow into the pool - grass clippings, leaves, flower petals, insects. Stuff that will rot given enough time. That also includes dead skin and snot. Inorganics would be sand and grit.

    High CYA and too low a FC level for the CYA is the most common problem here, by a huge margin. You can't feed a pool a steady diet of pucks and not have it happen. Unless the bottom of the pool looks like a peat bog, adequate chlorination will keep the algae away.

    Here's a little something I wrote a while ago that explains it.

    We'll take a 16000 gallon pool, because that's what I have. On a fresh fill, prominent national pool chain recommends 2.5 pounds pf stabilizer per 10,000 gallons, which works out nicely to 4 pounds which brings CYA to 30.

    With an average loss of 2 PPM/Day or 14 ppm/week, I'll have added 8.6 PPM/CYA if I used trichlor pucks perfectly. And they recommend a weekly "shock" of dichlor between 5 and 10 FC.... 2-3 oz per 10,000 gallons. Split the difference; I'll add 4 oz. CYA went up another .9.

    So..by the end of week one, I have added 9.5 more CYA. It is now 39.5. Mimimum FC for that is 3, so I'm probably okay.

    Week two, up to 49 CYA.
    Week three, 58.5. Minimum FC should be 5, but they recommend 3 as ideal, so the pool looks a bit hazy. So I'll toss in a little extra dichlor "shock" to jack FC up to 10. Which adds another 6.4 CYA. Keeping count? We're up to 64.9 now.

    That caught the algae just in time.. we had two weeks of good luck. A steady diet of pucks and 4 oz. "shock" each week only added another 19, up to 73.9 now.

    Week 6 it started looking funky, so we "shocked"it once again. CYA is up to 99.3. But minimum FC to keep algae at bay is 8, and we're still holding things to 3, because prominent national chain's preprinted sheet shows that as ideal. So algae got a toehold and the pool has a bit of a tint. So we throw two whole bags of dichlor in which jacks it another 7.6 by the time week 7 is over, we're at 116.4, because we had pucks in the floater the whole time.

    So...in 7 weeks, from 30 to 116.4. Let's say there are no more algae outbreaks because they sold me a huge bucket of phos-free and another of yellow-out monopersulfate "shock" Nothing but the pucks and the extra 4 oz of dichlor "shock" weekly. So the next 7 weeks added 66.5, which brings the total to 182.9 CYA.

    Now if we didn't understand this and things looked a bit hazy, we might throw an extra puck or two in the floater every couple weeks, which will drive it over 200 easily.
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    Mod Squad jblizzle's Avatar
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    Re: Organic Contaminants

    Please realize you definition of "shocking" is very different from our SLAM Process. Likely you just killed off most of the visible algae with what you did, but never eradicated all of it. And if your FC was too low for your CYA level, then it was starting to grow again immediately.

    Remember, it is not high CYA that is the problem ... it is having your FC too low for what the CYA level is. But, when the CYA gets high, the required FC levels become much too high as well: FC/CYA Chart
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    BoDarville's Avatar
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    Re: Organic Contaminants

    Quote Originally Posted by Richard320
    We'll take a 16000 gallon pool, because that's what I have. On a fresh fill, prominent national pool chain recommends 2.5 pounds pf stabilizer per 10,000 gallons, which works out nicely to 4 pounds which brings CYA to 30.

    With an average loss of 2 PPM/Day or 14 ppm/week, I'll have added 8.6 PPM/CYA if I used trichlor pucks perfectly. And they recommend a weekly "shock" of dichlor between 5 and 10 FC.... 2-3 oz per 10,000 gallons. Split the difference; I'll add 4 oz. CYA went up another .9.

    So..by the end of week one, I have added 9.5 more CYA. It is now 39.5. Mimimum FC for that is 3, so I'm probably okay.

    Week two, up to 49 CYA.
    Week three, 58.5. Minimum FC should be 5, but they recommend 3 as ideal, so the pool looks a bit hazy. So I'll toss in a little extra dichlor "shock" to jack FC up to 10. Which adds another 6.4 CYA. Keeping count? We're up to 64.9 now.

    That caught the algae just in time.. we had two weeks of good luck. A steady diet of pucks and 4 oz. "shock" each week only added another 19, up to 73.9 now.

    Week 6 it started looking funky, so we "shocked"it once again. CYA is up to 99.3. But minimum FC to keep algae at bay is 8, and we're still holding things to 3, because prominent national chain's preprinted sheet shows that as ideal. So algae got a toehold and the pool has a bit of a tint. So we throw two whole bags of dichlor in which jacks it another 7.6 by the time week 7 is over, we're at 116.4, because we had pucks in the floater the whole time.

    So...in 7 weeks, from 30 to 116.4. Let's say there are no more algae outbreaks because they sold me a huge bucket of phos-free and another of yellow-out monopersulfate "shock" Nothing but the pucks and the extra 4 oz of dichlor "shock" weekly. So the next 7 weeks added 66.5, which brings the total to 182.9 CYA.

    Now if we didn't understand this and things looked a bit hazy, we might throw an extra puck or two in the floater every couple weeks, which will drive it over 200 easily.
    I remember reading this from last year. This is one of the best write-ups I've seen illustrating the FC/CYA relationship using a typical scenario that most non-TFP pool owners go through.

    Doloskeeter, I would read and re-read the above post until you know it forward, backwards, and sideways. I would also familiarize yourself with the FC//CYA Chart that jblizzle referenced. If you study both of these until you fully understand the FC/CYA relationship, I guarantee your "organic contaminant" problem will go away regardless of what you plant near your pool.
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