Become a TFP Supporter Pool Math Forum Rules Pool School
Results 1 to 6 of 6

Thread: Algae growth within 1-2 days after presumably shocking

  1. Back To Top    #1

    Join Date
    Jul 2013
    Location
    Orangevale, CA
    Posts
    4

    Algae growth within 1-2 days after presumably shocking

    Problem:

    Algae growth within 1-2 days after presumably shocking the pool using 1 lb dichlor powder (3 bags total)


    Background:

    Since my pool is surrounded by oak trees, it usually starts the year (Feb/Mar) as a 25,000 gallon "petri dish". While removing leaves and cleaning filters 3-4x/week, I more or less used a combination of dichloc pool shock (more) and liquid chlorine bleach (less) and a liquid algae control product (3M product I purchased at Costco, sorry can't remember more than that about the algae control stuff). During this period I didn't take any measurements and relied on visual signs of improvement). Within 2-3 weeks, I could clearly see the bottom of the pool. In preparation to open the pool for the season in late Apr or early May, I added a water clarifier, increased pump runtime to finish cleaning the water, and continued shocking with mostly dichlor shock packages (3 packages 1x/week). (Test strips at this point indicated TC > 10 ppm, pH 7.5, TA 80 or lower) I use 2 pool floats, each filled with three 3-inch tabs for chlorine maintenance. (Can't say I test during the week, but my test strip always indicated zero chlorine before I started the weekly shock treatment). As the summer has gone on, especially with the high heat in the Western USA right now, algae growth has started to appear within a day or two after adding the dichlor.

    Current:

    I started seeking advice from several local pool stores a few weeks ago. One store had me treat for phosphates (>300), but that didn't seem to help. A second store indicated phosphates were still high (>300), additionally I had high nitrates (30), and their recommendation was to drain 30% of the pool water. Feeling frustrated, I searched the Internet and found the forums on this website. After a night of reading other posts, my immediate conclusions were to order the TF-100 test kit and that I needed to cease using any form of chlorine other than liquid bleach! So a few days ago I received the TF-100 test kit and ran a set of tests shortly after adding a gallon of 12.5% liquid chlorine:

    FC = 3.5
    CC = 1
    pH = 7.2
    TA = 200 (my test strip still reads 80)
    CYA = 100 or higher (* See note below)

    Based on the high CYA level, I went ahead and drained roughly 40% of the pool water. While the pool was draining, I opened up the pool light niches since a lot of the algae growth appears around the lights. I cleaned them out and they were full of green algae. I also partially scrubbed my pool walls in the areas where the algae shows up regularly. I re-filled the pool last night and did the following tests:

    FC = 2
    CC = 1
    pH = 7.3 to 7.4
    TA = 120
    CYA = 70 (* See note below)
    CH = 350

    I debated with myself about adjusting the pH with borax, but decided to just add liquid chlorine. After adding ~5.5 bottles of 12.5% chlorine, the FC = 37.

    I ran the chlorine test again this morning, FC = 20; and CC = 1, so I added more 3 more gallons of the chlorine which brought the FC back up to 34.

    Questions:

    Am I on the right track? Are there any adjustments I should make to my game plan?

    When do I know I'm done with the chlorine shock process? I'm assuming I'm looking to see CC < 0.5 and the fall in FC < 3-4 ppm/day. Is that right?

    Note:

    Being a rookie with the CYA test, I question my CYA test results. I think I need to run the test with better lighting, because I'm not sure I see the black dot or a reflection. Are there any posts in the forums with advice or tips about conducting the CYA test?


    Thanks in advance! I'm glad I found you guys!!
    In-ground; 25,000 Gallons; Plaster; Recreation/Lap Pool; TF-100 Test Kit
    Redundant Pump/Filter Combination each with a Sta-Rite 0.75 HP MAx-E-Glas II Pump and System 3 Cartridge Filter (300 sq.ft.)

  2. Back To Top    #2

    Join Date
    Aug 2010
    Location
    Dallas, TX
    Posts
    4,052

    Re: Algae growth within 1-2 days after presumably shocking

    Your CYA may still be too high. Let us know when you feel you have an accurate test result. You can pour the test back into the squeeze bottle and retry several times, don't be afraid to.

    Read through how to perform the shock process in Pool School.
    pool-school/shocking_your_pool

    Shocking is complete when:
    CC is 0.5 or lower;
    An overnight FC loss test shows a loss of 1.0 ppm or less;
    And the water is clear.

    You can read through this for help with your tests:
    extended-test-kit-directions-t25081.html
    Built in 1957 44,000 gallon in-ground, Wet Edge Primera Stone in Sky Blue, Intelliflo VF Pump, 600 lb. Pentair Triton II TR-100 Sand Filter, CircuPool RG 60 Plus SWG, TF-100 test kit
    If TFP has helped you, please click to SUPPORT TFP!

  3. Back To Top    #3

    Join Date
    Jul 2013
    Location
    Orangevale, CA
    Posts
    4

    Re: Algae growth within 1-2 days after presumably shocking

    I was able to re-run the CYA test tonight and my wife and I consistently came up with a reading of 60. My pool has a fairly large surface area and it does get quite a bit of direct sunlight from the late morning until 6:30 PM or so at this time of year. Should I look to lower the CYA to 50 at some point?

    When I got home from work today, I re-tested the water and found FC = 17 and CC = 0.5, so I added 3 gallons chlorine @ 12.5 % and got FC = 39 after brushing and allowing pumps to circulate for 30 mins.

    I re-tested again at about 11:30PM and FC = 28, CC = 1. Added 3 - 121 oz containers of bleach @ 8.75 % and which brought FC = 36.

    Pumps have been running continuously. I'll clean filters tomorrow just to be sure they're clean. Otherwise, I assume I stay the course at this time,and just keep monitoring the FC and CC. Anything else?

    Thanks for your assistance!
    In-ground; 25,000 Gallons; Plaster; Recreation/Lap Pool; TF-100 Test Kit
    Redundant Pump/Filter Combination each with a Sta-Rite 0.75 HP MAx-E-Glas II Pump and System 3 Cartridge Filter (300 sq.ft.)

  4. Back To Top    #4

    Join Date
    Jul 2013
    Location
    Orangevale, CA
    Posts
    4

    Re: Algae growth within 1-2 days after presumably shocking

    I should also mention the water looks very clear.
    In-ground; 25,000 Gallons; Plaster; Recreation/Lap Pool; TF-100 Test Kit
    Redundant Pump/Filter Combination each with a Sta-Rite 0.75 HP MAx-E-Glas II Pump and System 3 Cartridge Filter (300 sq.ft.)

  5. Back To Top    #5

    In the Industry

    duraleigh's Avatar
    Join Date
    Apr 2007
    Location
    Sebring, Florida
    Posts
    30,077

    Re: Algae growth within 1-2 days after presumably shocking

    It sounds to me like your pool is very close to completing the shock process. As mentioned above, you are done with that process when...
    1. Your pool water is sparkling
    2. Your CC's are .5 ppm or less
    3. You can hold your FC overnight without losing more than 1 ppm.

    Hold your FC up high (24 is good enough) and let the chlorine kill off the remaining organics.

    You are ready to perform the OCLT tonight or tomorrow night for sure to see if you can get your FC loss to 1 ppm or less and you are done.

    Leave your CYA @ 60.....that's fine.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

  6. Back To Top    #6

    Join Date
    Jul 2013
    Location
    Orangevale, CA
    Posts
    4

    Re: Algae growth within 1-2 days after presumably shocking

    Glad to hear you think I'm getting close to the end. I'm at two of three for the shock completion criteria. Water looks good, CC is at 0.5, but I still seem to be losing >10 ppm every 8 hours.

    Testing this morning found FC = 25 & CC = 0.5, added 4 gallons of 8.25% bleach and got back to FC = 41. I'll keep the FC up today and hope for the best tonight for the OCLT.

    Once I'm done with the shock process, I'll run another set of tests to see where I am with pH and TA once the FC comes back down to normal levels. Before I started the shock process, my TA was 120. Should I try to reduce that after getting done with the shock treatment?

    At some point, I figure I'll go through the borate process I've read about elsewhere on this forum.

    You guys have some great information!
    In-ground; 25,000 Gallons; Plaster; Recreation/Lap Pool; TF-100 Test Kit
    Redundant Pump/Filter Combination each with a Sta-Rite 0.75 HP MAx-E-Glas II Pump and System 3 Cartridge Filter (300 sq.ft.)

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •