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Thread: High CYA and Algae

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    Orinda, California
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    High CYA and Algae

    New to forum, have been browsing for about a month. I have been working hard on walls this summer Way too much algae. I believe it is because my CYA has increased to 125 from 100. I believe the only way I can lower the CYA is partially drain the pool and add water. I plan on doing this in January when the rain comes to Northern California. I will drain water as the rain starts and hope it rains like cats and dogs Add water from faucet to make up any difference as I can't have the pool pump not running for long. Hopefully this will lower the algae next summer via lowing the CYA. Can the forum please tell me if I'm on the right track? Also, any recommendations as to what granular chlorine to add without increasing CYA? Only other issue is high phosphate and pool store has me purchase expensive phosphate remover

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    Catanzaro's Avatar
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    Re: High CYA and Algae

    Here, at TFP, we do not recommend any phosphate remover. Under rare circumstances, will you ever need this again. In order for anyone on the forum to help you, we will need to have some test results. Unfortunately, test strips and pool store testing are not very reliable and it is recommended that you use only of 2 test kits. Most of us here use the TF-100. Also recommend purchasing with the XL-Option and the Speed Stir.

    Your CYA could easily be above 125. Exchanging water is the only way to reduce your CYA to appropriate levels to conduct a SLAM and finish it properly. Liquid bleach is what will be recommended to clear your pool up, not powdered chlorine or shock.

    It is recommend you start with Pool School and please add your signature.

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    14,700 gallons IG Pool Vinyl Liner - Octal Circulation System
    Hayward Pro-Series 350 LB. Sand Filter Model # S270T - 2" Plumping
    Hayward CL2002 Chlorinator - Hayward Super Pump 2 HP Model # k48m2n111
    Hayward AQR9 SWG 25K Salt Cell & TF-100 Test Kit + Speed Stir
    Gulfstream HE125RA - 117K BTU Heat Pump - Date of Build is 11-2013

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    Orinda, California
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    Re: High CYA and Algae

    thank Catanzaro. I added my profile after my post, my bad. I'll get a TF-100 test kit and read pool school.
    28,000 gallon IG pool, plaster, built approx. 1970.
    1 1/2 " plumbing. Pentair, Intelliflo 3 hp variable speed.
    Crystal Water cartridge filter system, model #425
    Dolphin Deluxe 4,

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    Catanzaro's Avatar
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    Re: High CYA and Algae

    TJTJ:

    While waiting on your test kit, I would recommend you brush the pool often enough to break up the algae and suspend it in the water. At this time, you should also be running your filter 24/7 and adding at least one gallon, if not two gallons of 8.25% straight unscented bleach. Assuming you ordered the TF-100 test kit. If so, here are a couple of video's to keep you busy for the next day or so:

    https://www.youtube.com/user/TF100TestKit

    Once you test for CYA, you will add enough liquid bleach to bring your TC levels up to SLAM and maintain it throughout the day. Chances are that you will add the bleach in the morning and during the evening, or as often as possible. This all depends on how bad the algae is. If water is to be exchanged, this should be done in small increments. Please edit your signature for either a plaster, vinyl, or fiberglass pool.
    14,700 gallons IG Pool Vinyl Liner - Octal Circulation System
    Hayward Pro-Series 350 LB. Sand Filter Model # S270T - 2" Plumping
    Hayward CL2002 Chlorinator - Hayward Super Pump 2 HP Model # k48m2n111
    Hayward AQR9 SWG 25K Salt Cell & TF-100 Test Kit + Speed Stir
    Gulfstream HE125RA - 117K BTU Heat Pump - Date of Build is 11-2013

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    Re: High CYA and Algae

    Catanzaro and or Other Forum members -
    I have one additional question. Your recommending replacing water in small increments. I go to pool math and the spreadsheet table seems to say the opposite. Example - I input that my current CYA is 125 and my goal is 40, the numbers crunch out a 68% water replacement. Seemingly suggesting 2/3 replacement at once. Highly possible I am missing something. Thank you.
    28,000 gallon IG pool, plaster, built approx. 1970.
    1 1/2 " plumbing. Pentair, Intelliflo 3 hp variable speed.
    Crystal Water cartridge filter system, model #425
    Dolphin Deluxe 4,

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    pabeader's Avatar
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    Re: High CYA and Algae

    There are 2 reasons they are suggesting smaller changes; In Cali most folks are worried about drought rules, and if you take too much water out at one time you could risk "floating" your pool.

    One big drain and refill would be better "less water overall" but isn't possible for some folks...
    Bob - Palm Beach by San Juan Pools. approx 5000 gals., Pentair 320 cartridge filter (all new guts installed by me), Goldline SWG, 'New to me' Kreepy Krauly Sand Shark, Intermec 104 Timer Test kit: TF-100 w/Speed Stir

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    Re: High CYA and Algae

    Considering you have a Plaster Pool, you can dump more than 1' at a time, maybe 2' at a time. If there are water restrictions and/or possible extra monthly charges, you can exchange water over a longer period of time. Your CYA will slowly come down over time, although you will have to maintain your appropriate FC level against your CYA level. Considering liquid chlorine (bleach) is not that expensive, you may go through a few extra gallons per month then you usually do. Remember that it is always safe to swim up to shock level. Chances are that you will keep pool open over winter and not use it too much, unless in an area where temperatures remain pretty hot.

    Once your CYA gets down to around 80, the pool becomes more manageable. Please keep us posted. You do not have to test for CYA every time you exchange 1' of water. I recommend testing CYA after 3 exchanges to see where you are at.
    14,700 gallons IG Pool Vinyl Liner - Octal Circulation System
    Hayward Pro-Series 350 LB. Sand Filter Model # S270T - 2" Plumping
    Hayward CL2002 Chlorinator - Hayward Super Pump 2 HP Model # k48m2n111
    Hayward AQR9 SWG 25K Salt Cell & TF-100 Test Kit + Speed Stir
    Gulfstream HE125RA - 117K BTU Heat Pump - Date of Build is 11-2013

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    Orinda, California
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    Re: High CYA and Algae

    Quote Originally Posted by Catanzaro View Post
    Considering you have a Plaster Pool, you can dump more than 1' at a time, maybe 2' at a time. If there are water restrictions and/or possible extra monthly charges, you can exchange water over a longer period of time. Your CYA will slowly come down over time, although you will have to maintain your appropriate FC level against your CYA level. Considering liquid chlorine (bleach) is not that expensive, you may go through a few extra gallons per month then you usually do. Remember that it is always safe to swim up to shock level. Chances are that you will keep pool open over winter and not use it too much, unless in an area where temperatures remain pretty hot.

    Once your CYA gets down to around 80, the pool becomes more manageable. Please keep us posted. You do not have to test for CYA every time you exchange 1' of water. I recommend testing CYA after 3 exchanges to see where you are at.
    I keep pool open year around as I live in the SF Bay Area. The lowest temp. is probably around 35 degrees. Major water restrictions! I was planning on replacing in late December as it is the rainy season here and we are supposed to get lot's of rain. I was planning on draining maybe 1/3 to 1/5 and hoping for rain and if not enough adding from faucet. Thanks.......

    - - - Updated - - -

    Quote Originally Posted by TJTJ View Post
    I keep pool open year around as I live in the SF Bay Area. The lowest temp. is probably around 35 degrees. Major water restrictions! I was planning on replacing in late December as it is the rainy season here and we are supposed to get lot's of rain. I was planning on draining maybe 1/3 to 1/5 and hoping for rain and if not enough adding from faucet. Thanks.......
    meant to say I would check weather forecast first. When major rain starts I would drain some portion of the pool and then rain and small amount of faucet would replace.
    28,000 gallon IG pool, plaster, built approx. 1970.
    1 1/2 " plumbing. Pentair, Intelliflo 3 hp variable speed.
    Crystal Water cartridge filter system, model #425
    Dolphin Deluxe 4,

  9. Back To Top    #9

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    San Rafael, CA USA
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    Re: High CYA and Algae

    Sounds like a good plan. Orinda gets average annual rainfall of 24" so 2 feet. Hopefully this year will be higher than this. 2 feet out of an aveage 4.5' pool depth would be a 44% water dilution. If you lower the water level some so that you don't overflow, be sure to turn off your auto-fill if you have one. Also, a pool cover will help to prevent evaporation and you generally want to minimize that because it removes only water and not CYA, CH, etc. from the pool.

    I live in San Rafael and have an electric automatic safety cover, but I use a cover pump where I pump winter rains into the pool to dilute the water each year. That helps keep the salt level in check (usually to between 900-1400 ppm) and generally refreshes the water.
    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
    12 Fafco solar panels; Purex Triton PowerMax 250 natural gas heater (200,000 BTU/hr output); automatic electric pool safety cover; 4-wheel pressure-side "The Pool Cleaner"

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