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Thread: Question about shocking and FC afterward

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    Question about shocking and FC afterward

    My readings were:

    Hardness = 250
    TC = 1
    FC = .5
    Ph = 6.4
    TA = 60
    CYA = 20

    I'm using strips until my Taylor test kit gets here. I decided to shock the pool with 4 gallons of chlorox. Checked 3 hours later with filter running. Here are my results:
    TH = 250
    TC = 5
    FC = 0
    Ph = 7.0 which is probably not correct since it was just shocked.
    TA = 120
    CYA = 20

    Does this make sense? TC went up but FC went down. Could I be getting a bad reading because I'm using strips? Shouldn't FC go up after shocking? Should I shock at night instead?
    10000 gal round above ground pool
    Hayward cartridge filter 1.5hp

  2. Back To Top    #2

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    Test strips are not the best thing to use.

    You need to wait until your pool has turned over to retest accurately. 3 hours is probably way too soon.

    It is best to add chlorine at night, but if you are too low, you do need to add some regardless of the time of day.
    Buggs

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    Re: Question about shocking and FC afterward

    Skibender,

    What does your water look like? Are you shocking to clear a cloudy, murky pool or is your water clear?

    Secondly, yes, the strips are not very good to do what you want. They're more of an approximation.

    Tell us about the condition of your water and we'll get you a course of action that'll keep you in good shape 'til your Taylor kit gets there.
    Dave S. - Forum owner
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

  4. Back To Top    #4
    Guest
    Some test strips will bleach out at high chlorine levels, It depends on what reagent chemisty they are using. Even the same manufacuter might use different reagents in different strips for the same test (LaMotte,for example, uses different chlorine test reagents in their InstaTest 5 and their InstaTest6 strips.) Also, your TA doubled! Shocking would not cause that to happen! It just once again illustrates the unreliability of test strips except for a quick check on chlorine levels (and an OTO dipcell is almost as fast and much more dependable!)

  5. Back To Top    #5
    You guys are great. Excellent responses.
    Yes, I'm trying to rid cloudy blue water. I started out my 1st experience with a pool that had green water with lots of algea. Based on recommendations from this site, I've eliminated the green algea. It's now a nice blue but cloudy. After I removed the algea, I started working on 1 test at a time. 1st I corrected hardness. Then I corrected TA. Now I figured I'd go after the cloudiness. I agree, these strips are not very accurate.
    I tested again this a.m. Numbers are similar:
    TH=250
    TC=2
    FC=0
    PH=6.8
    TA=100
    CYA=20

    I've been running the filter the whole time. Water still looks the same. I have a cartridge Hayward filter with 1.5 hp. Pressure gauge runs 5-9 lbs. When I first started using the filter my pressure was only 1lb. I cleaned the cartridge yesterday and now it seems to have more pressure which doesn't make sense also. Doesn't the pressure go up when it is getting plugged?
    Hopefully my chlorine numbers are out of whack because of the test strips. My Taylor test kit should be here tomorrow. I think I ordered the K-2005. They said it was their best kit. Maybe I'll keep filter running and continue to brush until test kit arrives. I did notice some leaves at the bottom while brushing. I'll continue to work on removing them. I think the previous owners didn't take care of the pool very well. Thanks for everyones help. I'll take as many suggestions as possible.
    10000 gal round above ground pool
    Hayward cartridge filter 1.5hp

  6. Back To Top    #6
    JasonLion's Avatar
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    It can take a week for the filter to clear the water and you may need to clean the filter a couple of times. How did the cartridge look when you cleaned it?

    That pressure sounds kind of low. A supply side blockage can cause low pressure and sometimes turning the pump on and off will shift the blockage and cause the pressure to vary. You should check the skimmer and pump strainer basket to make sure they are clear.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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    Skibender,

    You're on the right track. I would suggest this in the following order.

    1. Get a box of 20 mule team borax and put about a pound of it in your pool, then check pH a few hours later. you need to be up in the low 7.s on average. You may need a little more but bring it up in increments.

    2. While your at the store, get some bleach....10 gallons would be a good number

    2a. If there's a pool store close, get a new pressure guage...sounds like yours is faulty. Very common problem that's easy to fix for less than $10.00

    3. After you've put in the borax, download "bleachcalc" from the forum.

    4. Use "bleachcalc" to bring your chlorine up to at least 15ppm...no less. I know you can't test for it right now but the calcs will be ok.

    5. As soon as your test kit arrives, test for FC and bring it right back up to 15ppm...18-20 wouldn't hurt now that you can test accurately.

    6. Keep your pump running and your filter cleaned during this whole process.

    Keep testing and keep adding bleach to keep your chlorine level somewhere between 12-20 and your pool will clear pretty quickly. Report your progress.
    Dave S. - Forum owner
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

  8. Back To Top    #8
    Once again - thanks.

    The cartridge filter was pretty grimy. I used my water hose set on jet to spray it out. Lots of junk came out. Before I cleaned it, the pressure pretty much stayed at 1 lb. The water pressure coming out of the inlet was barley noticable. Now after cleaning it, it has pretty good force. I have the jet pointing slightly downward and to the side. I cleaned the strainer and also the filter (sort of like a strainer basket) before the pump. They are now all clean. I brushed again this morning before work and not much debris is stirring up so I think I'm making progress. I figured this would all take some time. Comparing the pool when I opened it to now is a hugh improvement. I'm happy so far. Now I just need to get it dial in. I bought borax yesterday but haven't added it. I'm not sure if my Ph reading is correct with the strips. I wanted to wait until my test kit arrives to be sure. No use in adding unnecesary chemicals. The only thing I will do until my kit gets here is shock again with clorax. I know this won't hurt my situation. I will probably clean the filter again tonight. It seems to be working pretty good though. A new pressure gauge won't hurt. My filter won't stay at a constant pressure. I hear it "working" harder. That's when the pressure increases and the pressure of water coming out of the outlet increases. It seems to be filtering pretty well so I'll leave that issue alone until I get my chemicals correct.

    Thanks for all the help and info. I'll keep everyone posted with my numbers after my test kit arrives. Then I will be sure of my numbers. Right now, who knows for sure. I might be chasing my tail with these strips.
    10000 gal round above ground pool
    Hayward cartridge filter 1.5hp

  9. Back To Top    #9
    I finally received my Taylor test kit. Checked a few parameters this morning before work. Didn't get time to test CYA - had to get to work. Here's the latest:
    I put 5 gallons of clorax in 2 nights ago with filter running for the last 5 days non-stop. Last night couldn't do anything with the pool because of baseball games. My readings this a.m. were:
    FC=0
    TC=.3
    PH=7.2
    TA=130

    I'm amazed that my FC is 0. Per the cal's on this site, when I superchlorinated 2 nights ago, I should've been close to 20ppm with FC. My pool water is still cloudy so whatever is in there is really using up the chlorine. Does that sound correct? I asked the wife to mix up 5 more gallons today and add it. The chlorine should be working good because my Ph is pretty close. I've kept my solar cover on also to help prevent the sunlight from eating up the chlorine. I think as everyone has suggested, I'm going to continue to superchlorinate until my FC stays at an acceptable range. Does this seem logical to everyone?
    10000 gal round above ground pool
    Hayward cartridge filter 1.5hp

  10. Back To Top    #10
    JasonLion's Avatar
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    That sounds like a pretty typical experience for algae in the water. Keep adding bleach to bring it up to shock level as often as possible.

    Keep in mind that high chlorine levels can sometimes discolor or damage solar covers.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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    Ski,

    While the solar cover protects your chlorine, unfortunately, it also hinders the elimination of combined chloramines.

    Get your CYA up to speed, keep your chlorine WAY up there despite loss to the sun and the bugs in your pool, and, if it were me, I'd remove the solar cover....sounds like your pool needs to "breathe" a little.
    Dave S. - Forum owner
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

  12. Back To Top    #12
    Thanks for the suggestions. I'll remove the cover after work tonight. What are combined chloramines? Is that the same as combined chlorine?
    When I think algea, I think of the large chunks but I suppose that is also what is keeping my water cloudy - correct? Algea can be real small also which is why I have cloudy water - am I thinking correct on this?

    Since I didn't get a chance to superchlorinate last night and my FC was 0 this morning, did I defeat my purpose of superchlorianting 2 nights ago? Obviously, keeping the FC at 15-20 ppm will eventually clear my cloudy water up - if I miss a day and not keep FC at 15-20, will it still clear up if I get it back to 15-20?

    Do I want to keep FC at 15-20 until the water clears up? I will check all my levels again tonight and get all other chemicals in spec.
    10000 gal round above ground pool
    Hayward cartridge filter 1.5hp

  13. Back To Top    #13
    JasonLion's Avatar
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    Algae is constantly growing, even while the chlorine is killing it. The more algae there are the faster they grow. The more chlorine there is the faster you kill them. It's a race where you are trying to kill them faster than they grow until you get them down to zero. If you skip a day the algae gets to pull ahead and get a couple of laps in front of you. If you skip two or three days you might as well be starting from scratch. The more frequently you can bring the chlorine level up, the further ahead you get, the sooner it will all be over.

    "Chloramines" are combined chlorine.

    Algae are really really small. They tend to stick together and form mats, which is how we normally see them. When they die, and sometimes even when they are alive, the mats tend to break apart and you get cloudy water.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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  14. Back To Top    #14
    Well, I'll try to keep up on the FC better. Here's my latest readings from tonight.
    FC=0
    TC=1
    PH=7.2
    TA=140
    CH=150
    CYA=20

    I need to get my FC and CYA up and TC down. By research from this site, I super-chlorinated to lower my TC. I'll send the wife to get some CYA tomorrow so everything stays a little more stable. The good news is, the bottom of my pool is appearing. This wouldn't have been possible for a newbe like me to go it alone. Thanks for everyone's help. If anyone has any other recommendations based on my latest numbers, I'm all ears.
    10000 gal round above ground pool
    Hayward cartridge filter 1.5hp

  15. Back To Top    #15

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    I would wait to add the CYA until after your algae has completely cleared and the chlorine level holds overnight. Your slightly lower CYA is a good thing as it will make the chlorine level more effective (relative to higher CYA) and should have you clearing your pool of algae faster. Remember that you may need to vacuum to waste if algae collects on the bottom of the pool and may need to use a skimmer sock if you have a lot of algae and prefer changing skimmer socks to more frequently cleaning the filter. (In the unlikely event that you do not have a floor drain and have poor circulation near the bottom of the pool, then a flocculant may be required). Mostly, you just need to stay on top of the chlorine keeping the FC level up.
    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
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  16. Back To Top    #16
    Chemgeek - that makes complete sense to me. I checked FC and PH this morning before work. My FC is holding now. I was at 1.5. PH was 7.2. I added some Clorax to bring the FC up. I think I'm pretty close. The pool looks clearer. Not perfect yet but getting better. I have the filter running constantly. I think my circulation is ok. I'm not really sure how I tell. The kids are going to jump in today for the first time. I'm sure that will help stir things up. I will keep the FC towards the high end of the spec. That should help me clear things up faster. CYA at 20 isn't too low so I'll leave it there as suggested until crystal clear water. Thanks for the help.
    10000 gal round above ground pool
    Hayward cartridge filter 1.5hp

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