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Thread: SLAMing but FC not rising

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    SLAMing but FC not rising

    Hello,

    My water turned cloudy after heavy rain. Admittedly, I hadn't treated the pool with any chemicals for a couple weeks before that. So I found this web site and decided to try the TFPC method. Yesterday I got the pH down to around 7.2 using Sodium Bisulfate (couldn't find muriatic acid anywhere in town). Then, I started to SLAM this morning, since the FC level was zero. The CYA is around 25-30 (tested using TF-100), so I read that the shock level is around 12 or 13 for that CYA. We have a 25,000-gal vinyl above-ground, with sand filter.

    I started adding bleach this morning (4 gallons at a time) and testing every 2 hours with the FAS/DPD test from the TFTestKits TF-100. The FC hovered all day around 0.5 to 1.5. I figured I still needed to get the FC level up, so I KEPT adding bleach all day long. So far, in ONE day, I have added 28 gallons of 8.25% concentration Clorox (I had gone to Sam's and bought 10 of the Clorox 3-gallon boxes). Water is still cloudy, and FC never came up. It was a very sunny day in Tennessee, so maybe with the CYA level and sunshine, that's why the FC never rose?? CC rose once to 5.5 but then went back down and stayed near FC level all day. Our pool is in direct sunlight all over -- 33 ft circular diameter, 4 ft deep, so that's a lot of surface area to let the sun destroy the chlorine.

    Anyway, it is evening now, and I just added 3 tri-chlor tabs to add a little CYA (yes, I know, not part of BBB method, but I had some left over). FC just came up to 2.5 within last 2 hours -- but that may be due more to tri-chlor than bleach?

    Questions:

    1. Will adding this amount of bleach in one day hurt my vinyl liner? If so, what to do to reverse damage?
    2. Should I have started my SLAM process at night? I fear I have wasted all this money today.
    3. Should I go buy some cyanuric acid for stability, and then restart SLAM? But that would require even MORE bleach to reach shock level. Sheesh!
    4. Should I stay the course (following PoolMath calculator, which tells me to add 3-4 gallons of bleach each time) indefinitely, and trust that FC will eventually rise?

    Thanks,
    Joel

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    Mod Squad JohnT's Avatar
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    Re: SLAMing but FC not rising

    Welcome to TFP!

    You could easily go through 12 or 13ppm of chlorine in two hours. Testing and dosing once an hour at first isn't excessive.
    TFP Moderator
    20K Gallon 20X36 Vinyl Inground
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    Re: SLAMing but FC not rising

    Welcome to the forum Please add your pools info to your signature as outlined here http://www.troublefreepool.com/conte...etting-started

    Testing once an hour at the beginning of a SLAM in not only not excessive it's recommended.

    If you know your CYA and you are using the CYA chlorine chart you will not damage your liner. If you damaged your liner there is no reverse.
    It's better to start at night but the soon your start the better. The more often you test and bring the FC back to or slightly above your SLAM level the better. Always add at night as you do get the best bang for your buck when the sun it down.
    When doing a SLAM you want the lowest reasonable CYA level possible (20-30ppm). But getting it that low isn't always possible.

    If you don't trust and believe you won't fix your pool. We have all done it and it can be a pain, expensive and seem like there is not end. There is an end and all you need to do is read a couple threads from people who followed the advise here and cleaned up their "swamps". If they can do it, so can you.

    With a CYA of 30 you should be adding enough bleach to hit 12ppm and then try to maintain it there. The longer you maintain it the shorter your SLAM will be. The more times it drifts well below 12 the longer and more bleach $$$ you'll need to complete the SLAM.

    How about posting your pools current water test
    '70s IG Vinyl 32K gal, Lazy L, Hayward SuperPump 1.5hp 120V, S240 Sand Filter W/DE
    Solar Blanket, Well Water, Borax Added, TF-100 tester. ? too cold
    1979, 275gal Conway Emerald Spa P-100-2, ES-2 Spa Pack, bromine floater, indoor
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    Re: SLAMing but FC not rising

    Just tested all values again, with TF-100 test kit:

    pH 6.8
    FC 1.5
    CC 2
    CH 150
    TA 130
    CYA 45 (hope I did CYA right. I was getting 25-30 earlier today. But I did put 3 tri-chlor tabs in this evening. That's the only reason I can think of for the jump.)

    Water = Cloudy.
    25K gal, AG vinyl, sand filter, TFTestKits TF-100

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    Re: SLAMing but FC not rising

    Tri-chlor caused your pH to drop and CYA to increase.
    This is the reason why we recommend using bleach/liquid chlorine for SLAMming a pool.

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    Re: SLAMing but FC not rising

    Welcome to TFP

    The trichlor will raise your CYA which you probably don't want while SLAMing pool. It wouldn't raise it by as much as your posted test results that quickly. Did you do that CYA test indoors at night at the time you posted? That could account for a different reading as that test should be don't in sunlight with your back to the sun. It is the test that takes the most getting used to. You can do the test several times with the same water sample by pouring from the viewing tube back into the mixing bottle and re-do test. That can help in getting comfortable with it.

    Your last set of test results posted CC of 2 but you didn't post FC. Was that maybe your FC amount?

    I would double check CYA when it's sunny. Check FC and CC. Keep SLAMing. Post results and ask questions here.
    18*36*23 true "L" vinyl IG 29,000 gallons. SWG. TF-100 test kit.
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    Re: SLAMing but FC not rising

    Well, maybe it was all about not having the right CYA reading. Here are this morning's results (saw no need to retest CH -- vinyl pool):

    FC 0.5
    CC 1
    TA 140
    CYA 50 (Did this test this morning 2 times with back to sun, so I was in the shadow. I had been doing test indoors.)
    pH 6.8

    PoolCalc says shock level for my FC/CYA is 20, which is 753 oz of 8.25% bleach, or ~6 gallons. I had been doing 4 gal at a time because I mistakenly thought CYA was 30.

    I guess it's time to try again...

    So, this will make 34 gallons of bleach put in in about 24 hours. I just kind of want some confirmation that I don't have to worry about an upper limit of bleach added, and that FC/CC are all that matters when SLAMing -- i.e., not the amount of bleach added. I don't want to take a bath in Clorox, if you can understand. I'm just imagining putting like 30 more gallons in today (whether that turns out to be true or not). Does that sound feasible for a 25,000-gal pool that's just cloudy - not green?

    Sorry if I sound paranoid. I've just always relied on pool stores to tell me what to do. Now that I'm doing it myself, I'm just trying to get over the hump of ignorance. I appreciate everyone's advice.

    Thanks,
    Joel
    25K gal, AG vinyl, sand filter, TFTestKits TF-100

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    Re: SLAMing but FC not rising

    It "sounds" like a lot of bleach to me but if you are testing and your FC is dropping then SOMETHING is consuming it. I would add the pool math recommended dose and test again within an hour or two and redose if needed. Your rate of consumption of bleach will eventually diminish as it's doing its job. You do want to keep it at SLAM level until you pass all three tests.

    No CC's
    Clear water
    Pass OCLT
    18*36*23 true "L" vinyl IG 29,000 gallons. SWG. TF-100 test kit.
    http://tftestkits.net/splash-page.html

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    Re: SLAMing but FC not rising

    BEFORE you start to SLAM again raise the pH to 7.2 Once you start your SLAM the pH won't be reliable so you need to adjust it before you start to dump in more chlorine.

    Can you post a picture of the cloudy water ?? You have something in there eating chlorine as the CC level is showing but it would be nice to see what it is you are seeing just in case you have algae starting on top of some other problem.

    There is no upper limit if you are adding the recommended amount of bleach for your level of CYA. Bleach/chlorine gets used up by "stuff" in your pool and eaten by sunlight. If you're asking if 34 gals is too much, no it isn't. Too much is adding more than what is recommended and that's what can damage pool equipment or a liner. If you had algae hiding under a ladders step, behind a skimmer door or in a light niche and it isn't found and killed you will have to keep your SLAM going for hundreds of gallons of bleach as it will always show up eating chlorine and a higher CC level.
    Easiest to think of the gallons of bleach you have already added, they are gone. They were used up killing something and they aren't in the pool and you won't be swimming in them or in the gallons to come. The daily dose of chlorine you need to maintain a pool is what you actually swim in and it's so low you won't even smell it. Even at SLAM level it's safe to swim in it and it's likely you can't smell chlorine then either.

    If you follow what everyone here does for SLAM and maintenance you will have a sparkly blue pool with sanitary water that's a joy to swim in and easier and cheaper to maintain than going to the pool store. You just need the patience to follow it through.
    '70s IG Vinyl 32K gal, Lazy L, Hayward SuperPump 1.5hp 120V, S240 Sand Filter W/DE
    Solar Blanket, Well Water, Borax Added, TF-100 tester. ? too cold
    1979, 275gal Conway Emerald Spa P-100-2, ES-2 Spa Pack, bromine floater, indoor
    TF-100, Best test kit - TFTestkits.net
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    SLAMing but FC not rising

    What's the condition of your sand filter and what is the circulation of water like in your pool? Are you running your pumps 24/7 while SLAMing?

    One thing that can eat up a lot of chlorine is a dirty sand filter. You may want to back wash it or, if you have the time and energy, consider deep cleaning it.

    Also, make sure you're getting good water draw from your skimmer and good water flow at your pool returns. Poor circulation can cause your FC to not mix well.



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    Re: SLAMing but FC not rising

    Here is a thread showing what and how to "deep clean" http://www.troublefreepool.com/threa...-a-Sand-Filter
    '70s IG Vinyl 32K gal, Lazy L, Hayward SuperPump 1.5hp 120V, S240 Sand Filter W/DE
    Solar Blanket, Well Water, Borax Added, TF-100 tester. ? too cold
    1979, 275gal Conway Emerald Spa P-100-2, ES-2 Spa Pack, bromine floater, indoor
    TF-100, Best test kit - TFTestkits.net
    Please help keep the lights on, become a TFP Supporter!

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    Re: SLAMing but FC not rising

    Added some Borax and then SLAMmed all night long - got up every hour and added bleach as needed to keep FC up to 20. (I am sleepy!) Now, it is the next afternoon, and the water is clear, and every few times I check, the FC will be at shock level when I check, so I don't add bleach those times. Things are looking up. I am now a believer. I realize that I might need to keep this up for a little bit because the FC DOES drop some between tests, and the CC is consistently at 1 when I test, but no huge FC drops like before. The FC dropped from 20 to 14 during six hours of cloudy daylight today -- but that's OK. It's better than drops of 12 or 13 in two hours like I was seeing a few days ago when I wasn't SLAMming at a high enough bleach level.

    And I can definitely stress to people to NOT make the same mistake I did - always test CYA outdoors with back to the sun! Otherwise, you may get too low a CYA reading, and if you attempt to SLAM, you may not get the FC high enough to stay around any time at all -- and that definitely means more $$$ in bleach. Live and learn.

    Thanks to all!
    25K gal, AG vinyl, sand filter, TFTestKits TF-100

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    Re: SLAMing but FC not rising

    I love it when a plan comes together!
    27' AG 18K Gallons ~ Cartridge Filter ~ Pentair 1.5 HP Pump

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    Re: SLAMing but FC not rising

    Now that your plan is coming together remember you need to have clear water, CC is .5 or less and you do the OCLT (ie overnight FC loss test shows a loss of 1.0 ppm or less). Don't quit early on us and turn green again
    '70s IG Vinyl 32K gal, Lazy L, Hayward SuperPump 1.5hp 120V, S240 Sand Filter W/DE
    Solar Blanket, Well Water, Borax Added, TF-100 tester. ? too cold
    1979, 275gal Conway Emerald Spa P-100-2, ES-2 Spa Pack, bromine floater, indoor
    TF-100, Best test kit - TFTestkits.net
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    Re: SLAMing but FC not rising

    Update on SLAM:

    So it has been 3 days now since I started the SLAM (with the proper bleach amount). Water has been clear for a couple days. I read on another thread that someone's water cleared up, and an expert posted that the OCLT should succeed by the next day. Well, my OCLT keeps failing. Still losing about 5 ppm FC by each morning. Also, CC is still almost CONSTANTLY at 1 (or so I think -- see below). So I'll keep SLAMming -- so far, I have gone through ~ $200 worth of bleach, and bought another $100 worth (30 gal 8.25%) today. I had not been backwashing, so I read that I should probably be backwashing once every 2-3 days. So I backwashed this morning. My pressure gauge hasn't worked in a few years (I don't think it every really worked properly since we bought the house w/pool 5 years ago), so I have no clue when backwashing is needed. I see NO algae anywhere and haven't for a few days. I brushed the sides yesterday morning. Should I still brush daily, when it looks like there's nothing to brush in crystal clear water? I'm doing due diligence and keeping it up to shock level of 24 (CYA test looks to be between 50 and 60, so I'm going with CYA level being 60).

    As for testing (I have TF-100 w/SpeedStir), should I be counting EVERY drop, or subtract the last one? Seems like I read somewhere on the forum that you subtract the last drop. I ALWAYS have to put in 2 drops in order for the CC test to clear up the 10mL sample. Always. No more, no less. Is this a reading of 1 or 0.5 ? If this is true, then should I be subtracting a drop from the FC test, too? (not that it matters yet -- but when the OCLT gets closer to passing, a 0.5 variance could mean the difference between success and failure!!)

    Anyway, if the CC test is really constantly at 0.5 (when I thought it was at 1), then I'm just waiting on the OCLT to pass. Patience, patience, patience. Bleach, bleach, bleach. $100, $100, $100...
    25K gal, AG vinyl, sand filter, TFTestKits TF-100

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    Re: SLAMing but FC not rising

    Replace that gauge. It is cheap and easy to do. You can get them at Harbor Freight, Northern Tools, etc. You don't have to go to the expensive pool store.

    When performing the FC test, once the solution turns clear, you are done. Nothing to add or subtract. The removing the last drop has more to do when you are doing tests where you have to make sure the color change has completed, such as the TA test.

    Don't stop what you are doing. I walked a friend through this a couple of years ago, it took him 3 solid weeks to get through it. He was very doubtful about halfway through. Before doing this, he had troubles every year because of smelly water, algae on his steps, it was always something and he hated having his pool. I talked to him about his pool a couple of weeks ago and he told me he has never had another problem with his pool or water. This year he hasn't done anything other than test and add chlorine and it has been sparkling clear.
    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
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    Re: SLAMing but FC not rising

    You're doing great! Keep after it. Be sure to scrub problem areas such as ladders and lights. Remove them and give them a thorough brushing with diluted bleach solution. Overnight chlorine losses and continued CCs are an indication that chlorine is still battling something in your pool.

    When I perform the FAS-DPD test, I add drops until it's clear, then one more to make sure it doesn't change any more. That last drop does not count when calculating FC. Then I add the R-0003 reagent for CC. That last drop for the FC assures me that I've gotten to the FC end point and can get an accurate CC reading. It may skew the CC test slightly lower than actual but I've had the most consistent results that way.
    Joel - TFP Moderator - Minnesota - **Become a TFP Supporter!** Helpful Links: ABCs of Pool Water Chemistry - SLAM Procedure - Chlorine/CYA Chart
    40x20 Pool: 32K Gallons * Vinyl * Bleach Chlorination * Hayward S270T Sand Filter * Pentair SuperFlo 1 HP * Teledyne/Laars Heater * AquaVac Tigershark * TF-100 w/ SpeedStir
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    Re: SLAMing but FC not rising

    Your water is clear but your CCs indicate you are still burning up dead algae and organics. You need to keep it up until those CCs go down. I would not perform any 25ml (0.2 ppm / drop) FC/CC tests until CCs measure 0.5 or less.

    The pressure gauge needs to be replaced and you need to backwash and possibly deep clean your filter. Once you start killing the algae, it all settles on the filter and then the filter becomes a concentrated reservoir of dead algae and organic waste. That will be the most likely source of your CCs. By backwashing your filter you can flush that waste out.

    The end point of any test is complete color change. For chlorine, it is pink-to-clear transition. You can look at the test water at a slight angle to see if there's any pink. The drop that produces full clarity is your last drop and should be counted.

    For TA, it's the drop that produces RED, not the drop before that which produces a brownish color (mixed green & red).

    All tests are assumed to be +/- 1 drop. That is your tests accuracy.



  19. Back To Top    #19

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    Re: SLAMing but FC not rising

    Thanks, Sunny. I plan to try a deep clean this evening to see if it helps. Haven't even cracked the filter open in 3 years or so (when we did a sand replacement).

    http://www.troublefreepool.com/threa...-a-Sand-Filter
    25K gal, AG vinyl, sand filter, TFTestKits TF-100

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    Re: SLAMing but FC not rising

    You can get a gauge mailed out from the same place you get the test kit : http://tftestkits.net/Pressure-Gauge...Mount-p77.html
    '70s IG Vinyl 32K gal, Lazy L, Hayward SuperPump 1.5hp 120V, S240 Sand Filter W/DE
    Solar Blanket, Well Water, Borax Added, TF-100 tester. ? too cold
    1979, 275gal Conway Emerald Spa P-100-2, ES-2 Spa Pack, bromine floater, indoor
    TF-100, Best test kit - TFTestkits.net
    Please help keep the lights on, become a TFP Supporter!

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