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Thread: Draining to Lower CYA

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    Draining to Lower CYA

    Hi Guys,

    Been lurking for for about a week now and finally decided i had to post.

    Just moved in to our new home a week ago and got started on the pool. Pool was previously maintained by a pool guy. He did a poor job. DE filter without a multiport valve so I can't backwash. I'm going to have to remove the filters and hose them off. Current pressure at 15. Hayward pump runs for about 8 hours a day. I'm also using the Aquabot I used at my old house.

    Water is crystal clear but here are the numbers:

    FC - 11.8
    PH - >8
    CYA - 360 (After diluting sample, this number may be off)

    I am going to drain about 85% of the water on Monday (Weekend vacation). My question is..... Do I have to slam the pool once filled even though I don't have an algae problem?

    FYI.... I'm going to be using Chlorox Bleach, Borax, and Baking Powder. Some conditioner if the level drops below 30 after refill.

    Thank you guys in advance. This forum rocks.
    IG Kidney Shaped 32x15 (Approximate width) 18,500 gallons. Plaster. Pentair FNS Plus D.E. Filter (No Multiport Valve). Hayward Superpump 1 1/2 HP. Using the Taylor K-2006.

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    svenpup's Avatar
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    Re: Draining to Lower CYA

    You should do an OCLT (overnight chlorine loss test) to see if you have organics. With that CYA and the fact that it hasn't been getting a lot of attention I would be surprised if you didn't need to SLAM.

    Are you sure it is a DE filter? Removing the filter and hosing it off sounds a lot like a cartridge filter. Maybe they said they added DE to the cartridge filter and you misunderstood?
    TFP Method Advanced Intermediate
    • 17,500 gallons - In Ground - Plaster - Hayward Swimclear 3020 Cartridge Filter - Sta-Rite Max-E-Glas Main Pump upgraded with A.O. Smith B2980 E-Plus New Centurion Two-Speed Motor - Polaris 280 Cleaner with Polaris PB4-60 Booster Pump - TightWatt2 Timer - Taylor K-2006 Test Kit - Pool Pilot Digital Nano SWCG

    Helpful Links: Pool School, BBB for Beginners, How to Shock (hint...it's a process not a product), Chlorine/CYA Chart, Jason's Pool Calculator

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    Re: Draining to Lower CYA

    I performed an OCLT a couple of days ago and my FC dropped from 13 to 11.9. I'll add chlorine tonight and perform another tomorrow morning. I've been trying to keep FC around 13 until I actually drain and fill.

    Definitely a DE filter. It's a Pentair FNS Plus. Whoever installed it, probably the old pool guy, didn't bother to throw in a multiport valve.

    Last week, old pool guy knocked on my door to offer his services and part of his sales pitch was that he would replace my DE Filters once a year and add conditioner before summer and after summer. It was at that point that I knew he had no idea what he was doing. When he came by he did mention that it had been a week since he last serviced the pool. Pool wasn't neglected but was treated with something that raised the CYA through the roof.
    IG Kidney Shaped 32x15 (Approximate width) 18,500 gallons. Plaster. Pentair FNS Plus D.E. Filter (No Multiport Valve). Hayward Superpump 1 1/2 HP. Using the Taylor K-2006.

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    svenpup's Avatar
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    Re: Draining to Lower CYA

    How did you get FC of 11.9? If you are using the FAS-DPD test you should use a 10ml sample which will give .5ppm per drop. Even if you are using the 25ml sample I think that is .2per drop.
    TFP Method Advanced Intermediate
    • 17,500 gallons - In Ground - Plaster - Hayward Swimclear 3020 Cartridge Filter - Sta-Rite Max-E-Glas Main Pump upgraded with A.O. Smith B2980 E-Plus New Centurion Two-Speed Motor - Polaris 280 Cleaner with Polaris PB4-60 Booster Pump - TightWatt2 Timer - Taylor K-2006 Test Kit - Pool Pilot Digital Nano SWCG

    Helpful Links: Pool School, BBB for Beginners, How to Shock (hint...it's a process not a product), Chlorine/CYA Chart, Jason's Pool Calculator

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    Re: Draining to Lower CYA

    Used 25ml sample and had 59 drops to get colorless. Sorry, typo, it was 11.8.

    So....Should I SLAM after filling or just get my chemistry levels balanced after filling?
    IG Kidney Shaped 32x15 (Approximate width) 18,500 gallons. Plaster. Pentair FNS Plus D.E. Filter (No Multiport Valve). Hayward Superpump 1 1/2 HP. Using the Taylor K-2006.

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    svenpup's Avatar
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    Re: Draining to Lower CYA

    You should switch to the 10ml sample. No need for that much precision.

    Go ahead and slam since you OCLT was > 1. Should be an easy one.
    TFP Method Advanced Intermediate
    • 17,500 gallons - In Ground - Plaster - Hayward Swimclear 3020 Cartridge Filter - Sta-Rite Max-E-Glas Main Pump upgraded with A.O. Smith B2980 E-Plus New Centurion Two-Speed Motor - Polaris 280 Cleaner with Polaris PB4-60 Booster Pump - TightWatt2 Timer - Taylor K-2006 Test Kit - Pool Pilot Digital Nano SWCG

    Helpful Links: Pool School, BBB for Beginners, How to Shock (hint...it's a process not a product), Chlorine/CYA Chart, Jason's Pool Calculator

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    Re: Draining to Lower CYA

    Quote Originally Posted by svenpup View Post
    You should switch to the 10ml sample. No need for that much precision.

    Go ahead and slam since you OCLT was > 1. Should be an easy one.
    Awesome. Thank you for the feedback. I will report back with the initial test once the pool has been filled.

    Have a great weekend.
    IG Kidney Shaped 32x15 (Approximate width) 18,500 gallons. Plaster. Pentair FNS Plus D.E. Filter (No Multiport Valve). Hayward Superpump 1 1/2 HP. Using the Taylor K-2006.

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    Re: Draining to Lower CYA

    Update.... Starting draining around 8:30 p.m. on Sunday night. Drained about 80% and then started filling at about 2:00 A.M.

    Wife finished with the fill this morning. Just got home and tested chemistry with the following results:

    FC: 1.5
    PH: 7.6
    TA: 210
    CYA: 60

    CYA was still a little higher than what i was shooting for (50) but it is much more manageable than the over 400 it was at before draining it. Added the MA and Chlorine Liquid (518 oz) to bring it up to SLAM level of 24.

    Just one question. I was low on MA so I didn't input the TA levels into Pool Math. Pool Math said to add 60 oz of 14.5 MA to lower PH to 7.2 but if input a TA of 210 it says to add 129 oz. I didnt want to drop PH too low so I only added the 60 oz. Should I pick up some MA and add the additional 69 oz of MA it suggested?

    FYI... Pool is crystal clear after fill and I still don't see any signs of algae. Slamming for precautionary reasons.
    IG Kidney Shaped 32x15 (Approximate width) 18,500 gallons. Plaster. Pentair FNS Plus D.E. Filter (No Multiport Valve). Hayward Superpump 1 1/2 HP. Using the Taylor K-2006.

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    Mod Squad tim5055's Avatar
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    Re: Draining to Lower CYA

    At this point hold off on MA additions. Above 10 pH you can no longer accurately test. Hopefully it goes quickly. You can do an OCLT tonight to see how you stand. Did you test for CC after the fill?
    TFP Moderator 39 X 18 23,000(ish) freeform gunite; built 2007ish; Pentair Triton II TR100 600lb Sand filter; 2 HP Pentair pump with 2.2 HP AO Smith single speed motor; 2 skimmers, 1 main drain, 4 returns w/waterfall, Stenner 45MHP2 3GPD running@ 60% - 15 gal Tank; heated by the sun CYA 200+ when I started - 50 now. Dolphin Supreme M5 Pool Cleaner. Hot Springs SX Spa, 285 gallon

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    Re: Draining to Lower CYA

    Quote Originally Posted by tim5055 View Post
    At this point hold off on MA additions. Above 10 pH you can no longer accurately test. Hopefully it goes quickly. You can do an OCLT tonight to see how you stand. Did you test for CC after the fill?
    I did not do a CC test after the fill.

    Got home from the gym and tested chemistry. FC was at 16 and CC was at 0. Added chlorine and ran FC test about 40 minutes after and got a FC of 23.5, CC was 0. Hopefully I will lose <1 FC PPM and my SLAM will be over. I plan on leaving the pump running until I have a successful OCLT. Sun has been intense in SoCal so I'm going to make sure I'm up before any direct sunlight has hit the pool and burned off any chlorine.

    I'll update tomorrow morning after I have tested FC and CC.

    Thank you.
    IG Kidney Shaped 32x15 (Approximate width) 18,500 gallons. Plaster. Pentair FNS Plus D.E. Filter (No Multiport Valve). Hayward Superpump 1 1/2 HP. Using the Taylor K-2006.

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    Re: Draining to Lower CYA

    Tested this morning and got FC at 20.5 and CC at 0 (Approximately 9.5 hours since last night's 23.5 FC result). I brought the FC back up to SLAM level (24). Will check the FC and CC when I get home this afternoon. I'll add chlorine then and then I'll perform another OCLT tonight.

    Thanks again.
    IG Kidney Shaped 32x15 (Approximate width) 18,500 gallons. Plaster. Pentair FNS Plus D.E. Filter (No Multiport Valve). Hayward Superpump 1 1/2 HP. Using the Taylor K-2006.

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    Re: Draining to Lower CYA

    Like you said, your diluted cya test was probably a little off. 20% of 360 is 72, so, it may very well have been 300 instead.
    Pool size: 24000gal inground Vinyl-Taylor k-2006 and k-1766 test kits and-speed stir
    Intermatic P1353ME digital timer w/freeze sensor
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    Polaris 280 vacuum/Polaris PB4-60 boost pump
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    Re: Draining to Lower CYA

    Quote Originally Posted by timerguy View Post
    Like you said, your diluted cya test was probably a little off. 20% of 360 is 72, so, it may very well have been 300 instead.
    Definitely off. But a CYA at 60 is much more manageable than what I was working with before. I was shooting for a cya in the 40-50 range but I cut it a little short.

    I figure with splash out, filter cleanings, and some rain my CYA will fall within the 40-50 range for next season. I want to add borates once I figure out the rhythm my pool.
    IG Kidney Shaped 32x15 (Approximate width) 18,500 gallons. Plaster. Pentair FNS Plus D.E. Filter (No Multiport Valve). Hayward Superpump 1 1/2 HP. Using the Taylor K-2006.

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    Re: Draining to Lower CYA

    Update.

    Tested again when got home from work and got fc at 19 and cc at 0.

    Added chlorine and will test when I get home from gym. Sun has been intense all day. I'm hoping that is what burned it off and not something living in the pool.

    Will update...
    IG Kidney Shaped 32x15 (Approximate width) 18,500 gallons. Plaster. Pentair FNS Plus D.E. Filter (No Multiport Valve). Hayward Superpump 1 1/2 HP. Using the Taylor K-2006.

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    Re: Draining to Lower CYA

    Came home from gym and fc was 21.5. I think my volume may be off or something because I added enough to get up to 24 before I left. My pool is kidney shaped so getting an accurate volume is tough.

    Added anoth 59 ounces to get it up to 24. Tested after 30 minutes and got fc at 23.5 and cc at 0.

    Am I expecting this to be over too quickly? Starting to get a little frustrated.
    IG Kidney Shaped 32x15 (Approximate width) 18,500 gallons. Plaster. Pentair FNS Plus D.E. Filter (No Multiport Valve). Hayward Superpump 1 1/2 HP. Using the Taylor K-2006.

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    Mod Squad tim5055's Avatar
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    Re: Draining to Lower CYA

    Sometimes it's quick, sometimes not so much.

    You should only consider FC levels that you test, not "calculated" levels. While you may expect an outcome by adding a certain amount of chlorine (or other chemical for that matter) you should always test to verify where it ended up. Variables may include the volume as you note, but also the strength of the chlorine you use. It may not be up to it's advertised strength.

    Patience will win.
    TFP Moderator 39 X 18 23,000(ish) freeform gunite; built 2007ish; Pentair Triton II TR100 600lb Sand filter; 2 HP Pentair pump with 2.2 HP AO Smith single speed motor; 2 skimmers, 1 main drain, 4 returns w/waterfall, Stenner 45MHP2 3GPD running@ 60% - 15 gal Tank; heated by the sun CYA 200+ when I started - 50 now. Dolphin Supreme M5 Pool Cleaner. Hot Springs SX Spa, 285 gallon

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    Re: Draining to Lower CYA

    Thank you for the advice. I think tested too soon after I put in the chlorine and it hadn't thoroughly mixed.. I stepped out to buy more chlorine anticipating that I would have to add more tonight but when I tested it I got an fc level of 24.5 and a cc of 0.

    I'm going to use that for my oclt. I will report back in the morning.
    IG Kidney Shaped 32x15 (Approximate width) 18,500 gallons. Plaster. Pentair FNS Plus D.E. Filter (No Multiport Valve). Hayward Superpump 1 1/2 HP. Using the Taylor K-2006.

  18. Back To Top    #18

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    Re: Draining to Lower CYA

    I tested this morning when I woke up and got an FC of 24 and a CC of 0. Pool is crystal clear and I have no signs of algae (Never did see any algae but I'm now convinced I had something living in there).

    I think this means I'm done with my very quick SLAM. Now on to maintenance.

    Thank you to everyone who posted.

    Next project..... Borates.
    IG Kidney Shaped 32x15 (Approximate width) 18,500 gallons. Plaster. Pentair FNS Plus D.E. Filter (No Multiport Valve). Hayward Superpump 1 1/2 HP. Using the Taylor K-2006.

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    Mod Squad tim5055's Avatar
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    Re: Draining to Lower CYA

    Great job!!

    Now, if it were me I would hold off on the borates for a couple of months. Get to know your pool and it's needs first. I have considered them but with a German Shepherd Dog and 4 cats that think it's their water bowl I feel it's off the table for me.
    TFP Moderator 39 X 18 23,000(ish) freeform gunite; built 2007ish; Pentair Triton II TR100 600lb Sand filter; 2 HP Pentair pump with 2.2 HP AO Smith single speed motor; 2 skimmers, 1 main drain, 4 returns w/waterfall, Stenner 45MHP2 3GPD running@ 60% - 15 gal Tank; heated by the sun CYA 200+ when I started - 50 now. Dolphin Supreme M5 Pool Cleaner. Hot Springs SX Spa, 285 gallon

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    Re: Draining to Lower CYA

    No cats or dogs but I'm with you. Gonna take a few months to get familiar with my pool then I will see about borates.

    Thanks again.
    IG Kidney Shaped 32x15 (Approximate width) 18,500 gallons. Plaster. Pentair FNS Plus D.E. Filter (No Multiport Valve). Hayward Superpump 1 1/2 HP. Using the Taylor K-2006.

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