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Thread: Hardness level?

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    texascajuns's Avatar
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    Hardness level?

    Hello All,
    Hope someone can help me figure out my hardness problem and how to correct it since the 15
    year old at the pool store could not help. I currently test chlorine, pH, and TA at home but follow up with pool store test every couple of weeks to check other chemicals. I had to drain about 20% of the pool a couple of weeks ago because I had too high salt contect and my SWG was not working, so that was done. Now, here are my readings this week:

    FC = 3
    TC = 3
    CC = 0
    pH = 7.8 (added a little MA to drop it)
    Hardness = 375 (store recommends 200 - 300)
    TA = 85
    CYA = 50

    Does anyone know how to reduce hardness? Any help is greatly appreciated.

    Thanks,
    Shawn
    15k gal IG gunite pool with 7' spa. 1.5hp Jandy pump.
    Jandy Aquapure SWG and Jandy Cartridge Filter.
    Polaris 280 cleaner. TF-100 test kit.
    Sunstone Aggregate finish.

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    Mod Squad JohnT's Avatar
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    Re: Hardness level?

    Your hardness is on the high end of acceptable. Continued evaporation and refill could cause your hardness to climb if your fill water has significant hardness, so you could get too high. I would have your fill water tested to see if it is going to be an issue. If the fill water is low hardness, your pool's CH should drop naturally from rain water dilution.
    TFP Moderator
    20K Gallon 20X36 Vinyl Inground
    Hayward S244T Sand Filter with 1HP Whisperflo Pump. Liquidator C-201 and Solar Heat

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    frustratedpoolmom's Avatar
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    Re: Hardness level?

    I agree with John, as long as your other numbers are stable your CH should be fine.

    What are you using to 'shock' your pool? Some shock products, esp some powdered forms contain calcium, one is "calcium-hypochlorite" and that can raise your CH number. So if by chance you are using that I wouldn't anymore, just shock with straight liquid chlorine a.k.a bleach.
    Helpful links: Pool School; CYA/Chlorine Chart
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    Re: Hardness level?

    It is my understanding with gunite pools that the exact numbers for your TA and CH are not as important as your CSI number. You can determine your CSI with JasonLion's PoolCalculator.

    My CH was around 450 last year. It just takes a little extra vigilance when your numbers are on the high side to keep your CSI balanced.

    I agree with the other posters, your numbers look fine.

    Ron
    ~30000 GAL In-Ground 26'x50' Kidney Shaped Pool
    Hayward EC-75 DE Filter w/1.5HP Hayward SuperPump
    daily user of JasonLion's Poolcalculator
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    texascajuns's Avatar
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    Re: Hardness level?

    Thanks all for the advice, I'll keep watching the numbers for a couple of weeks.

    Frustratedpoolmom: I use liquid bleach to shock

    John: I will get my fill water tested

    Ron: I'll keep an eye on the CSI (that is new to me)

    Thanks again all, have a great day!
    15k gal IG gunite pool with 7' spa. 1.5hp Jandy pump.
    Jandy Aquapure SWG and Jandy Cartridge Filter.
    Polaris 280 cleaner. TF-100 test kit.
    Sunstone Aggregate finish.

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    texascajuns's Avatar
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    Re: Hardness level?

    All,
    Hopefully someone will see this again. I drained my pool and it brought the hardness level
    down but then a month later. The hardness is back up to 350 range. I tested my fill water
    and it has a hardness of 200. So, not trusting the pool store on my hardness rising again,
    I purchased the TF-100 test kit.

    Got the TF-100 2 days ago and now my hardness level is testing at 700, 2 days in a row.

    1. Can the hardness rise from 350 to 700 in a week? Pool store test on 8/4 was 350.

    2. How can i keep my hardness from rising so much?

    3. What am I doing wrong for with the test kit? Tested the fill water and it tested at 200.

    Water is clear, but I am seeing a white water line on the tile, is this because of the hardness?
    Any help is greatly appreciated.

    Thanks,
    Shawn
    15k gal IG gunite pool with 7' spa. 1.5hp Jandy pump.
    Jandy Aquapure SWG and Jandy Cartridge Filter.
    Polaris 280 cleaner. TF-100 test kit.
    Sunstone Aggregate finish.

  7. Back To Top    #7
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    Re: Hardness level?

    Is your pool store using a LaMotte colorimeter like the Waterlink Express and LaMotte reagents? there is a known limitation with this system when the CH is beyond the range of the meter and it will read low. Trust your results from the TF100.

    Also, how new is your pool?

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    Rockcrawler's Avatar
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    Re: Hardness level?

    Texascajun,

    I am in El Paso and struggle with Calcium Hardness as well, when I first started managing my pool myself 2 yrs ago, my CH was in the 700s, I did the drain and refill thing a couple of times, my fill water is about 200 CH as well, I have managed to keep it between 400 and 450. It is quite possible that the pool store test was wrong, and the TF 100 is right. I would rely on the TF 100, really I would rely on the walmart HTH tester before the Pool Store, IMO I don't think your CH could rise from 350 to 700 in a week, I think your CH has always been at 700. When I installed my SWG it would scale up in about a week, until I got the CSI under control, if you keep it within the range, you will prevent scale from building up. My CH is currently 450 and my SWG has been free from calcium build up for 6 wks now.
    13,000 IG Plaster, 2hp whisperflo pump, 48 sq in pentair DE Filter, 1 skimmer, 2 eyeball outlets, 200 sq ft solar panels on second story, Auto Pilot SWG-36, Polaris ATV Cleaner

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    texascajuns's Avatar
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    Re: Hardness level?

    Waterbear,
    sorry but i am not sure what the pool store is using to test my water, but they gladly sold me a $30 bottle of cleaner for the tile. Not going back anymore. Our pool is about 3.5 months old.

    Rockcrawler,
    Thanks for the help. I am trying to figure out this CSI thing, this is new so I don't quite understand it yet and how to control it. The pool calculater is saying that i should replace 57% of the pool water with new, wow, reads .96 csi.

    I am starting to think that the CH has always been high, because this white water line just keeps coming back after i clean it with acid!

    Guess I will have to drain again. Wow, did not expect this.
    15k gal IG gunite pool with 7' spa. 1.5hp Jandy pump.
    Jandy Aquapure SWG and Jandy Cartridge Filter.
    Polaris 280 cleaner. TF-100 test kit.
    Sunstone Aggregate finish.

  10. Back To Top    #10
    mas985's Avatar
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    Re: Hardness level?

    I am pretty use to running my pool at very high CH. I have very hard fill water (>350 pppm) during the summer so every year in February when fill water hardness drops to 50 ppm, I do a partial refill to bring the level down to 250 ppm or so. Last I measured CH it was north of 550 ppm. By the time next Feb comes around, it could be well above 700 ppm.

    Because of the fill water, I decided some time ago to work with what I have rather than fight it. This is not too much of problem unless the PH gets high which can cause scaling. So I have an automatic acid feeder and try to keep the PH below 7.7 which seems to keep the scale at bay.

    Bottom line is that you have find what works for you. It is a good idea to test the fill water during different parts of the year because depending on the water district and the water sources, the level can change significantly during the year. This way you know when the best time of year is for a refill. This should reduce the maximum CH that you might see during the year.
    Mark
    Hydraulics 101; Pump Ed 101; Pump and Pool Spreadsheets; Pump Run Time Study; DIY Acid Dosing; DIY Cover Roller
    18'x36' 20k plaster, 1/2 HP 2sp pump, Aqualogic PS8 SWCG, 420 sq-ft Cartridge, Solar, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater

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    texascajuns's Avatar
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    Re: Hardness level?

    Here are the rest of my numbers, sorry i didn't post earlier:

    FC - 2.5
    CC - 0
    CH - 700
    PH - 7.8
    CYA - 30 (i made this adjustment yesterday)
    TA - 100
    15k gal IG gunite pool with 7' spa. 1.5hp Jandy pump.
    Jandy Aquapure SWG and Jandy Cartridge Filter.
    Polaris 280 cleaner. TF-100 test kit.
    Sunstone Aggregate finish.

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    JasonLion's Avatar
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    Re: Hardness level?

    With CH around 700, I suggest you try to keep your PH below 7.8 at all times. With your numbers where they are now, you are very close to scaling.
    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

  13. Back To Top    #13
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    Re: Hardness level?

    Quote Originally Posted by texascajuns
    Our pool is about 3.5 months old.
    New plaster,this is not uncommon. The calcuim is leaching from your plaster. It is a water balance issue or a startup issue.

  14. Back To Top    #14
    texascajuns's Avatar
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    Re: Hardness level?

    Must be a water balance issue, cause i can not seem to control the pH, it bounces to 8.2 every 3 days, even though I hit with an entire gallon of acid, it will still be up there in a few days
    15k gal IG gunite pool with 7' spa. 1.5hp Jandy pump.
    Jandy Aquapure SWG and Jandy Cartridge Filter.
    Polaris 280 cleaner. TF-100 test kit.
    Sunstone Aggregate finish.

  15. Back To Top    #15
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    Re: Hardness level?

    Quote Originally Posted by texascajuns
    Must be a water balance issue, cause i can not seem to control the pH, it bounces to 8.2 every 3 days, even though I hit with an entire gallon of acid, it will still be up there in a few days
    This is actually normal for new plaster (less than a year old)

  16. Back To Top    #16
    JasonLion's Avatar
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    Re: Hardness level?

    You need to add acid more frequently to keep the PH from getting that high. If you continue to allow the PH to get very high you will almost always get calcium scaling which is rather difficult to remove.
    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

  17. Back To Top    #17
    texascajuns's Avatar
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    Re: Hardness level?

    Thanks all for the help and advice.

    Shawn
    15k gal IG gunite pool with 7' spa. 1.5hp Jandy pump.
    Jandy Aquapure SWG and Jandy Cartridge Filter.
    Polaris 280 cleaner. TF-100 test kit.
    Sunstone Aggregate finish.

  18. Back To Top    #18

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    Re: Hardness level?

    My CH is 625 and has been for the last two seasons (that is when I started doing my own testing). I keep my TA between 70-80 to control the PH rise. I find with this I only have to add acid every couple weeks depending on how much evaporation I have to make up for. My fill water is 200ppm in CH and TA.

    If you keep your TA lower you can easily manage this CH level though it is a little more work.

    I have been running my SWG for two seasons now as well and there has been no scaling on it at all. I just checked three days ago.

    With your TF100 in hand you should not have to worry about anything. You could do a partial drain if you wanted, but I just think that is such a waste of water.
    15,500 gal, inground gunite pool with 7 ft spa, 2 speed pump 2hp/.33hp, 3/4 hp booster pump, Intermatic P1353 timer, AutoPilot SC-48, Sand filter with ZeoBest, Heater, that I never use . . .

  19. Back To Top    #19
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    Re: Hardness level?

    I have a similar problem with CH and in addition to eliminating any calcium-based chemicals am doing my best to keep the pH correct. Without regular acid it gets up to 8.2 and scales pretty bad.
    As far as cleaning a "bathtub ring", straight acid does the trick. You don't need any special product. I use a nalgene bottle of a type that is frequently used to dispense Iso Alcohol or other chemicals. It puts out a miniscule stream when squeezed and I can clean about 15 feet of tile with four ounces.
    I am lucky to have a pretty competent / honest pool store and they carry a good product that helps with the typical CH white ring problem I have. It isn't unusual to lose half an inch or more water per day, so some ring is inevitable. Since using the original dose back in April and adding 3 oz per week, no ring!

    I gave up fighting the hard water and between keeping my pH right and the additive, things have been lots better this season.
    15K IG, WetEdge technology lined pool, StaRite pump, Hayward DE filter, Hayward Navigator, Zodiac MX8 (junked).

  20. Back To Top    #20
    Rockcrawler's Avatar
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    Re: Hardness level?

    Quote Originally Posted by JasonLion
    With CH around 700, I suggest you try to keep your PH below 7.8 at all times. With your numbers where they are now, you are very close to scaling.

    Jason beat me too it, that is the only way to keep that white line from appearing, no matter what you have to do, even if you have to add acid everyday, keep the PH below 7.8
    13,000 IG Plaster, 2hp whisperflo pump, 48 sq in pentair DE Filter, 1 skimmer, 2 eyeball outlets, 200 sq ft solar panels on second story, Auto Pilot SWG-36, Polaris ATV Cleaner

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