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Thread: testing questions and some possible algea.

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    Join Date
    Sep 2015
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    testing questions and some possible algea.

    Hey guys I converted over about a month ago after seeing how high my CYA was and having some algae issues due to keeping the FC at 4-5 based on recommended levels(without taking CYA into account.). I drained about a third out, there has been a lot of evap and now with all the rain in the Carolinas had to drain about 4 inches out. That being said it still shows a CYA of 160-180.
    • In testing CYA I use my Taylor kit and mix 10ML of pool water with 30 ML of distilled for a 4:1 ration. Mix this well, fill to 7ML in the bottle and add 7ML of reagent. mix that and in the sight tube I get between 40-45 tried it a few times. This has been a fairly consistant number and I would have thought it would have dropped after the rain and such the last month but not so. Based on this I have kept the FC at 15 for the last month. I didn't have the FAS-DPD in my kit and used a 3:1 dilution and estimated around 5 so that should be around 15.
    • I got my new FAS-DPD addition kit yesterday and measured 18. I used a 2:1 dilution to save on reagent. I got 18 drops which s a FC of 9 and multiply by 2 to get a FC of 18. THis is acceptable to do this right? My CC was zero as adding the CC reagent didn't turn it pink.
    • I noticed that there was some algae on the walls, and the pool floor was covered in a greenish brown. Could this be dead algae? I would think with my FC in that range I shouldn't have a issue. Pool temp is around 65.
    • Since I had some algae I decided to do a FC demand overnight and today there was no FC loss and is zero. If there was a algae issue it should have dropped correct? Pool is crystal clear. I vacuumed it all up and let the filter run a hour and will clean filter out.
    • In order to test PH, I know anything over 10 gives you false readings. Is it acceptable to dilute 2:1 to bring test water to 9 and then do PH? I did that and got 7.4.


    So one thing I noticed is that my liner appears to be losing the its color in a couple places on the floor and pattern turning white. I am concerned that running that high of chlorine is fading my vinyl liner has anyone else had issues running that high of FC due to CYA and had liner failure? In order for me to eliminate the CYA I have to replace 80% of my water. Ive been advised not to remove more than 6-8" of water at a time with a vinyl pool, and then refill and repeat. However doing that its going to take a lot more than 80% as I am not removing it all at once. I am very tempted in trying that CYA reducing enzyme but its up in the air whether it really works. Bottom line is I need to get control of my CYA.
    Location Charlotte NC. Pool is a IG vinyl liner, 18X36 lagoon approx. 20,000 gallons odd shaped pool with different depths. 2 skimmers, 3 returns. Hayward 1HP pump, Hayward cartridge filter, Hayward chlorine feeder, Laars 250,000 BTU heater. Stenner pump with #2 tube for chlorine injection. Leslie branded Taylor test kit

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    Mod Squad jblizzle's Avatar
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    Re: testing questions and some possible algea.

    I don't understand your FAS-DPD 2:1 dilution claim? Use 10ml of water and each drop is 0.5ppm ... no need to dilute anything.

    A 15ppm FC is still way too low to eradicate algae with a CYA of over 160ppm. You need to follow the ShockLevelAndMAINTAIN Process and honestly should replace at least half the water first. But with all the rain and likely high ground water table, I would not want to drain too much at a time either.

    It is odd that you had no FC loss over night if you saw algae. Was the pump running overnight?

    Some say you can dilute the pH test ... seems odd to me though.
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    Re: testing questions and some possible algea.

    So my thought is that we measure chlorine in ppm. If I add distilled water my ppm would be 1/2 of actual ppm so I take the reading and multiply by 2. The reason is reagent use after using 36 drops to measure a FC of 18 the reagent won't last long. By diluting by 1/2 I use 1/2 reagent. Or am I off base? And yes I need to reduce CYA but with closing a few weeks off I am going to wait until next year and see where I am. Pool math is telling me min of 12 FC with my CYA so I figured 15 or so was fine. I guess question is why didn't FC drop overnight and why do I have 0 CC if there is algae? I am traveling this week should I bump the FC up? I've been putting 121 oz jug of 8.5 in every 2 days to keep it at 15. And quite honestly I didn't have the fas-dpd test until yesterday so been guesstimate using 2:1 dilution and my Taylor kit that goes to 10. I'll measure tommorow and see how much I drop to tell wife how much to add during week.definetly need the fas-dpd kit to measure with accuracy.
    Location Charlotte NC. Pool is a IG vinyl liner, 18X36 lagoon approx. 20,000 gallons odd shaped pool with different depths. 2 skimmers, 3 returns. Hayward 1HP pump, Hayward cartridge filter, Hayward chlorine feeder, Laars 250,000 BTU heater. Stenner pump with #2 tube for chlorine injection. Leslie branded Taylor test kit

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    robdac's Avatar
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    Re: testing questions and some possible algea.

    With a 3:1 dilution on the CYA you don't really know anything except that it's really high. You have possible testing error introduced by the dilution. You also have the subjectivity of the test itself. It certainly took me a while to get the hang of it even without dilution. The one thing you know for sure is that your CYA is way above where you would ideally like to have it. High CYA is seen pretty often on these boards. The solution is to fix the CYA problem first. You can still safely drain some water out of the pool even with the high water table. Everything else is a temporary fix to the CYA problem.
    11K gal IG screened-in plaster pool w/ spa
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    Re: testing questions and some possible algea.

    Agree but at the end of the season I am not going to try and fix the cya issue. We will see how it looks come March.
    Location Charlotte NC. Pool is a IG vinyl liner, 18X36 lagoon approx. 20,000 gallons odd shaped pool with different depths. 2 skimmers, 3 returns. Hayward 1HP pump, Hayward cartridge filter, Hayward chlorine feeder, Laars 250,000 BTU heater. Stenner pump with #2 tube for chlorine injection. Leslie branded Taylor test kit

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