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Thread: FAS/DPD doing crazy things

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    Rocket50's Avatar
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    FAS/DPD doing crazy things

    My FAS/DPD tests is showing crazy numbers. Tested this morning and FC was 17.5. Doing a SLAM so want the FC at 20. Put in 1/2 gallon this morning to bring FC to 19. Tested again when I got home from work. FC was 14.5. Added 2 gallons of 10% chlorine to bring it back to FC 20.5. Just tested and it is FC 27.5. Been using pool math and have everything dialed in correctly. What am I missing? What could be going on?
    33K, IG, vinyl liner, 15 years old (??), 20x40, 3-8 feet deep, Hayward pump 1.5 HP, Hayward S240 sand filter (300 lbs of sand), Dolphin Triton robotic cleaner, TF-100 test kit.

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    Mod Squad jblizzle's Avatar
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    Re: FAS/DPD doing crazy things

    Stronger bleach than expected? Smaller pool than expected?
    Jason, TFP Moderator
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    Mod Squad jblizzle's Avatar
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    Re: FAS/DPD doing crazy things

    Are you holding the reagent bottle vertically when doing drops and adding them one per second or so.?
    Jason, TFP Moderator
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    Re: FAS/DPD doing crazy things

    How many scoops? 1 or 2?
    14,000 Gal, InGround, Spa Attached, Satin-Matrix Northshore Tahoe Pebble-Tec, Remodel 6/15, Taylor K-2006 Kit, Pentair IntelliFlo Variable Speed Pump, Polaris 280 Sweep, Jandy CL460 Cartridge Filter, Solar Heated. Taylor K-2006 Test Kit

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    Rocket50's Avatar
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    Re: FAS/DPD doing crazy things

    Probably dropping quicker than 1 per second. Holding vertical now. Wasn't for the first few days of the slam but old chemistry class memories came back.

    - - - Updated - - -

    1 scoop.
    33K, IG, vinyl liner, 15 years old (??), 20x40, 3-8 feet deep, Hayward pump 1.5 HP, Hayward S240 sand filter (300 lbs of sand), Dolphin Triton robotic cleaner, TF-100 test kit.

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    Re: FAS/DPD doing crazy things

    10 % bleach from Walmart in the pool section. 20x40 foot rectangular pool, 3 feet to 8 feet. 32,900 gallons. Unless the bleach is stronger than what is advertised on the label... I don't know. This happened a few days ago as well.
    33K, IG, vinyl liner, 15 years old (??), 20x40, 3-8 feet deep, Hayward pump 1.5 HP, Hayward S240 sand filter (300 lbs of sand), Dolphin Triton robotic cleaner, TF-100 test kit.

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    Mod Squad jblizzle's Avatar
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    Re: FAS/DPD doing crazy things

    You might need a little more powder. The higher the FC, the more you need. You can not use too much, but too little can cause difficulty getting the end point.
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
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    Rocket50's Avatar
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    Re: FAS/DPD doing crazy things

    OK. Tested at 20 this morning. The pool is sparkly with minimal debris. No way it went through 7 FC's last night. Must be user error.
    33K, IG, vinyl liner, 15 years old (??), 20x40, 3-8 feet deep, Hayward pump 1.5 HP, Hayward S240 sand filter (300 lbs of sand), Dolphin Triton robotic cleaner, TF-100 test kit.

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    Mod Squad jblizzle's Avatar
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    Re: FAS/DPD doing crazy things

    What was the CC? It is certainly possible to lose that much overnight. Although I may not rule out user error yet.
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
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    Re: FAS/DPD doing crazy things

    That is why I went with the sample sizer and calibrated cylinders. To get consistent results. Also, speed stir is the BOMB.
    13700 gal, 32'x16'x54" AG oval, vinyl, Echo Canyon II, 8500 series, Narrow Yard, Safety Fence & Stair, Sta-Rite Crystal Flow T-210WF, 44 GPM, Hayward SP1580TL 1HP Pump, Aqua Luminator, Festiva wedding cake steps, March 2006, TFT-100, Speed-Stir, Sample Sizer. Avatar Credit: TJ Townsend

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    Re: FAS/DPD doing crazy things

    Quote Originally Posted by jblizzle View Post
    You might need a little more powder. The higher the FC, the more you need. You can not use too much, but too little can cause difficulty getting the end point.
    this was the solution for me with for consistency during a slam (also was trying to hold at 20 with CYA of 50). 2 scoops.
    14,250 IG Plaster (re-do coming soon, i see concrete in a few places) I do get what appears to be "sand" in bottom of filter, about a spray paint can lid full over a month) Sta-Rite S7M120 Filter, Century SQ1102 pump. solar heat (roof tubes) figure 8 kinda shape, waterfall at deep end at bench (rarely used, but now understand i can raise ph with it), Hayward Vac Ulta, Sacramento, CA

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    Rocket50's Avatar
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    Re: FAS/DPD doing crazy things

    CC has been 0-.5 from the beginning. I have been losing less and less FC each day and never lost more than 5 FC when I first started on 5/13. Kind of cloudy and rainy today and tested out at 19.5 tonite. So a .5 FC loss today during the day. Sounds like its time to order more DPD powder.
    33K, IG, vinyl liner, 15 years old (??), 20x40, 3-8 feet deep, Hayward pump 1.5 HP, Hayward S240 sand filter (300 lbs of sand), Dolphin Triton robotic cleaner, TF-100 test kit.

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