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Thread: Recovering from Algae - 1st day with Test Kit

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    Recovering from Algae - 1st day with Test Kit

    Pool looked a bit cloudy 5 or 6 days ago, and then 4 days ago (Monday) an algae bloom hit. Came VERY fast, possibly because the pool water temp was up around 95F due to the solar heater valve acting "backwards".

    Turned pump on 24/7 on Monday night and I put 3 jugs (576 oz) of 6% bleach into the pool.
    Then on Tuesday we took an early morning sample to local pool store, and had them run water tests. They came back with 5.0ppm FC and I think 1ppm CC. Figured we must still be having some activity, so put a 2.5 gallon jug of 10.5% chlorine in around noon on Tuesday and then another jug around 9PM Tuesday. Was looking better (not green but somewhat cloudy). Cleaned filter and kept pump running Tuesday night.

    Wednesday morning it was looking better (not green/slightly cloudy). Another pool store sample came back with 5.0ppm FC so we put another 2.5 gallon jug in around noon on Wednesday just to be sure.

    Thursday morning (today), pool looked pretty good. Dull, but decent. Pool store results came back as:
    5PPM FC (Hmmmmm).
    5PPM TC.
    0.0PPM Combined Chlorine.
    7.6 pH.
    125 PPM TA.
    375 PPM Calcium Hardness
    60 PPM Stabilizer
    4200 ppm TDS

    Pool store talked us into adding 3 cups of acid this afternoon to try to bring down the TA cause it was just over their high range of 125ppm. We did that around 2PM but now I regret it. The kids swam for a couple hours around 5:30PM.

    The good news is my test kit came today. Here are the results from this evening from my first ever self-tests taken around 8PM:
    30ppm FC (?!?!?!?!)
    1ppm CC (kids?)
    7.2 pH.
    60 PPM TA
    400 ppm CH
    20 ppm CYA
    Pool is clear but dull.

    Questions:
    1) Where did all that FC come from? The quick color match test showed off the chart and then the dropper test gave 30ppm (repeated 2x) so I think it's more reliable than the pool store. Still, with the sun shining on the pool ALL DAY, I'm surprised it was so high. No chlorine (other than the muriatic) was added since the pool store gave a reading of 5ppm today. Could the pool store test be that far off (5ppm vs 30ppm??)? It is kinda fishy that all of the tests they've done this week came in at 5PPM FC.

    2) Is it reasonable that the 3 cups of acid would drop the TA that much (125PPM down to 60PPM)?

    3) 20 ppm CYA vs the pool store's 60??? That test seems so subjective, but I did it twice. Frankly I could still see just a bit of a shadow of a dot both times. Every pool store test for the past 3 months has shown 60-70ppm stabilizer. In fact, when we first got the pool going (bought a short-sale), they had us add a bottle of granular stabilizer at one point (probably about 32oz bottle).

    4) How big of a deal is a warm pool (90-92F) to water chemistry? Everyone here likes it warm.

    5) What should I do next?
    10,000 gallon Solar Heated IG Pebble with 100 ft2 Cartridge Filter/Pump.

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    Richard320's Avatar
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    Re: Recovering from Algae - 1st day with Test Kit

    Not to insult you or anything, but what size sample did you use for the FAS-DPD Chlorine test? If it's 25 ml, each drop is .2 ppm. If it's 10 ml, then each drop is .5. It's an easy mistake to make; I use 25 ml for TA, but 10 ml for CH, and many's the time I started doing Ch with 25 ml and wonder why it won't change when I'm past where it should.

    The other thing to ask is how did the pool store test? Color matching blocks only go to 5; so do some test strips, and anything over 5 is recorded as 5.
    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
    Troublefree does not mean Maintenancefree. It's like brushing your teeth: You can spend a couple minutes a day and pennies a week or go to the dentist once a year and spend several thousand dollars.
    A pool is like a pet - you have to feed it every day, even the days you don't want to play with it!

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    JasonLion's Avatar
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    Re: Recovering from Algae - 1st day with Test Kit

    I have two theories, which disagree with each other completely.

    What color was the OTO chlorine test (drops turn the sample various shades of yellow which are compared to a color chart)?

    If FC is really around 30, the OTO test should have been very dark orange to brown. If it was, then you are doing the more complex FC/CC test correctly. As Richard320 said, many pool stores report FC levels above 5 as 5. In this case CYA must be higher than you got and closer to the pools tore number, or you would lose too much chlorine to sunlight to have gotten FC up to 30.

    If the OTO test was some shade of bright yellow, with no hint of orange, then you did something wrong with the FC test, and CYA probably is around 20.

    No three cups of acid did not drop TA that much. One or more of the test results are wrong, most likely the pool store results.

    With the water around 90+ degrees you use a little more chlorine each day, but otherwise everything is the same.
    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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    Re: Recovering from Algae - 1st day with Test Kit

    Thanks for the quick replies.

    The quick test for Chlorine was very dark orange.. so much so that it looked like I should have been using the pH color scale. I did it twice cause I thought maybe I had mixed up the reagents it was so far off from the color chart.

    I'm 99% sure I used the 10 mL sample size for the "Chlorine Only" tube like the directions on the inside of the box say. I was being pretty meticulous about following the instructions since I've never done it. Did it twice and same results both times.

    I wonder if maybe I got the Chlorine concentration WAY high on Tuesday/Wednesday by assuming the various pool store readings of 5ppm were accurate? I essentially put 7.5 gallons of 10.5% chlorine in the pool over the span of 24 hours (Tuesday thru Wednesday). Not sure how high it might have been, but according to the pool calculator that amount would take me from 4ppm FC to 85ppm FC if I had added it all at once. Of course the pool has received a good 18+ hours of full sun over the past two days. How much would a pool at 85+ppm FC drop during a day of full sun?

    I'm going to run both chlorine tests first thing in the morning (just to make double-dog sure I'm using the 10mL sample size).... Glad I bought the "XL Option!"
    10,000 gallon Solar Heated IG Pebble with 100 ft2 Cartridge Filter/Pump.

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    Re: Recovering from Algae - 1st day with Test Kit

    Pool is clear but dull.
    How does that water look this AM? The dullness should start to filter out pretty quickly now. While you're testing, I suggest ONE more test of the CYA. pour the sample in and out of the view tube as often as you like so you can do multiple viewings with the same solution over and over.....that'll get you comfortable with interpreting that test.

    If the CYA is still 20 or so, then you'll want to add a little more down the road but get your chlorine tuned in first...it's the more important in your case.

    And lest we forget....Welcome to the forum
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Re: Recovering from Algae - 1st day with Test Kit

    Pool looks clear, but was hard to tell if it is still dull in the early morning light.
    This morning's results (Had to rush off to work so I couldn't do the full battery of tests):
    28PPM FC
    0.5PPM CC (very slight tinge of pink when I added the 2nd reagent.. may not have noticed it had it not been for the bright LED's on the speedstir. 1 drop of the 3rd reagent cleared it up).
    pH approx 7.4. Hard to tell but it was between the 7.2 and the 7.5 colors (but closer to the 7.5).
    The OTO test is still off the chart (very burnt-orange) so I believe the FC value is probably accurate.

    Thanks for the welcome. I have been lurking for the past 3 months, and have found the advice to be very helpful.
    10,000 gallon Solar Heated IG Pebble with 100 ft2 Cartridge Filter/Pump.

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    Re: Recovering from Algae - 1st day with Test Kit

    Help???

    Another day of sunshine passed today and I tested the water around 9:30PM.
    FC: 20 PPM
    CC: 0.5 PPM
    pH 7.2
    TA 40 PPM
    CH 410 PPM
    CYA 20PPM

    If photobucket images work, here is the OTO test:


    Here is the CYA test at a point where I could barely see the dot:


    And the corresponding reading:


    Here is the CYA test at the point where the dot went invisible:


    And the corresponding reading:


    My question is:
    If I only have 20 ppm CYA, then why did my FC only drop from 28 PPM to 20 PPM today? Is it possible that I only have 20ppm CYA and the FC is only dropping by 8 PPM per day?

    I'm very confident in my results of the FC test since the OTO test seems to confirm that it is >>5PPM since it is dark orange.
    I'm as confident in the CYA test as one can be all things considered. Is it possible that I have a bad (weak?) reagent for the CYA test? I tried shaking up the bottle real good before tonight's tests. Just to confirm I'm doing it right, I fill the Mixing bottle up to the bottom of the label with pool water, and then top it off to the top of the label with the reagent, correct??? Then I shook it. Waited a minute. Shook it some more.... poured it back and forth at least 3 times before taking these pictures on the fourth time.

    Other than maybe a bad reagent, any other ideas?
    10,000 gallon Solar Heated IG Pebble with 100 ft2 Cartridge Filter/Pump.

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    Richard320's Avatar
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    Re: Recovering from Algae - 1st day with Test Kit

    Well, if it's any consolation, I experimented last year and reported 18ppm shopws up as hunter orange on the OTO test. So I'd say the 20 is correct. Which does nothing to solve the CYA mystery. Although, 8 ppm is still a pretty good loss if it's only due to sunlight. Meaning the algae is killed off.

    Fill a few bottles and take samples to a few different pool stores tomorrow is my only suggestion.
    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
    Troublefree does not mean Maintenancefree. It's like brushing your teeth: You can spend a couple minutes a day and pennies a week or go to the dentist once a year and spend several thousand dollars.
    A pool is like a pet - you have to feed it every day, even the days you don't want to play with it!

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