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Thread: Affect of low CH with SWG?

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    ITR's Avatar
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    Affect of low CH with SWG?

    Hey guys. I know CH is recommended to be 350-400 with an SWG and I'm wondering what the affect of having a lower CH is with an SWG. Here's the deal:

    Woke up this morning and the new SWG (installed earlier this week) is reading high salt. So I'm off to drain. My CH is at 375, but I will say I have been fighting a few scale spots...so I presume that number might be high for my particular pool. Since I need to drain about 15% of the pool to bring the salt down...I have started the drain. To bring my CH down to 350, I need to only drain 6%. I know I can add CH to the pool...but since I'm having scaling issues...what affect does a low CH have on an IGP pool with an SWG?

    Not once has the CSI been above .6...and this scale issue is my nemesis...so would having a lower CH be better...or would I risk some type of long-term damage to the plaster (which I definitely don't want)?
    ----
    15' x 29' 10,300 gal w/ spa, IG-Plaster (Stonescapes Tropics Blue), 2spd WhisperFlo pump (1.5hp WFDS-26), Pentair Clean and Clear CC200 cartridge filter, Pentair MasterTemp 300BTU heater, Clear o3, RS-8 iAqualink

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    Re: Affect of low CH with SWG?

    I wouldn't go below 350.

    What has your pH been like?
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    Re: Affect of low CH with SWG?

    I have a vinyl pool, so let me preface that someone else may correct me. I believe the higher CH range for a plaster SWG pool is to allow the TA to be lowered to control pH while maintaining a tolerable CSI limiting damage to your plaster. Are you pretty good at keeping pH between 7.5 - 7.8? High pH will drive scaling if not lowered.
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    Re: Affect of low CH with SWG?

    pH was constantly rising last year (new pool). Which is when the scale formed. It hasn't gotten worse this year. This year pH fairly constant with a slight rise over the week. I add about 4-10oz of MA each week.

    So why wouldn't you go below 350? Trying to understand the "why"....does is suck the calcium out of the plaster?

    And.... do I do two drains..or just one and then bring up the CH after the 15% drain?
    ----
    15' x 29' 10,300 gal w/ spa, IG-Plaster (Stonescapes Tropics Blue), 2spd WhisperFlo pump (1.5hp WFDS-26), Pentair Clean and Clear CC200 cartridge filter, Pentair MasterTemp 300BTU heater, Clear o3, RS-8 iAqualink

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    Re: Affect of low CH with SWG?

    In an SWG pool it is best to maintain a CSI below 0. Try to target your CSI around -0.1. In terms of absolute quantities, CH is irrelevant to an SWG, in fact, the lower the better. But, to a plaster pool surface, CH is important. So use CSI as your guide - adjust pH and TA to create a negative CSI. I would not try to lower or raise CH, just let it be what it is and adjust the other pool parameters.

    For reference, my CH is 850ppm (other people on TFP have CH up near 1000ppm) and I get no scale in my pool and my SWG never has scale in it. I simply adjust my pH and TA to get to the CSI I want.
    Matt
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    Re: Affect of low CH with SWG?

    Quote Originally Posted by JoyfulNoise View Post
    In an SWG pool it is best to maintain a CSI below 0. Try to target your CSI around -0.1. In terms of absolute quantities,
    Got it. And I try to keep my CSI negative (to work at loosening the scale...although I think it's a lost cause at this point....and I'm not about to do a full drain/acid wash). In fact, CSI has been negative since November of last year. Good to know I'm on the right track. The SWG is new this week...I felt I had a good handle on the balancing up until I had to worry about salt. I thought I was putting in less than I even needed for the minimum...but the SWG is registering high...so I must have over done it.

    Thanks for all the help guys.
    ----
    15' x 29' 10,300 gal w/ spa, IG-Plaster (Stonescapes Tropics Blue), 2spd WhisperFlo pump (1.5hp WFDS-26), Pentair Clean and Clear CC200 cartridge filter, Pentair MasterTemp 300BTU heater, Clear o3, RS-8 iAqualink

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    Re: Affect of low CH with SWG?

    Do you have a K-1766 salt test kit? This is the most accurate test. SWGs report salinity based on a conductivity measurement and they are not typically accurate to more than +/-400ppm. You need to make the SWG happy but it's good to know how far off the salt level is using a K-1766 test.
    Matt
    16k IG PebbleTec pool, 650gal spa, spillway and waterfall, 3HP IntelliFlo VS / 1.5HP WhisperFlo, Pentair QuadDE-100 filter, IC40 SWCG, MasterTemp 400k BTU/hr NG heater, KreepyKrauly suction-side cleaner Dolphin S300i robot, EasyTouch controls, city water, K-1001, K-2006 and K-1766 test kits, Mannitol test for borates

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    Re: Affect of low CH with SWG?

    I don't. But from what I have been reading I will be investing in one. Right now I have been using strips (I know...I know...not accurate either...but it's what I had in the pool test basket).

    You bring up a good point. When I get the kit I will need to calibrate the SWG.


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    Re: Affect of low CH with SWG?

    Not that it matters, but the Aquacheck strip is saying 3190.
    ----
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    Re: Affect of low CH with SWG?

    The Aquachek isn't terrible, that is what I have used for 4 years.

    Yes, keep your CSI more negative to work on brushing and reducing the scale that is there. Use a stainless steel brush and keep CSI -0.6 to -0.8.

    More here on scale, Pool School - Calcium Scaling
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    Re: Affect of low CH with SWG?

    Definitely have read that article...at least 20 times. I've never gone below -0.5. If you think it's safe to go down to -0.8, I'll give that a try. Just drained 3" off the pool and will see where it is this weekend when I do my full tests. I have been brushing with nylon (or some type of polymer) brush. I'll give stainless a try...I just don't want to damage the interior given it's only a year and a half old.
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    15' x 29' 10,300 gal w/ spa, IG-Plaster (Stonescapes Tropics Blue), 2spd WhisperFlo pump (1.5hp WFDS-26), Pentair Clean and Clear CC200 cartridge filter, Pentair MasterTemp 300BTU heater, Clear o3, RS-8 iAqualink

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    Re: Affect of low CH with SWG?

    It is OK to use a steel brush after one year. Plaster is fully cured after one year.
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    Affect of low CH with SWG?

    Thanks. I picked one up and will start using it. Another question. Before I added the salt, the pool was crystal clear. Now it's a bit cloudy. The salt was added about five days ago. I know you guys will ask so here are today's results:

    pH: 7.8 (added HCL to bring it to 7.4 this morning)
    FC: 5.5
    CC: 0.5
    CH: 300
    TA: 60
    CYA: 60

    It's not horrible...I can still see the vents in the drain in the deep end, it just looks like a lot of dust is suspended in the water. Especially at night with the lights on. Also, noticed the water today had a bit of a viscous look this morning. Ran the pump for about six hours today and the filter didn't clear it out.

    Any ideas?


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    15' x 29' 10,300 gal w/ spa, IG-Plaster (Stonescapes Tropics Blue), 2spd WhisperFlo pump (1.5hp WFDS-26), Pentair Clean and Clear CC200 cartridge filter, Pentair MasterTemp 300BTU heater, Clear o3, RS-8 iAqualink

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    Re: Affect of low CH with SWG?

    I hope you're not draining / refilling? A high salt reading doesn't matter unless it's not operating, so I would leave everything where it is. You may have overshot due to the salt that would have already been in the pool, but 3000/3500 ppm salt shouldn't be an issue.

    If I see a tinge of cloudiness, it's usually after a storm or a lot of kids swimming. I add a quart of chlorinating liquid (to eliminate anything that got added to the pool), brush it, run the cleaner, and then run the pump on low 24/7 until the cloudiness is gone. I might run the cleaner again, or brush it again to keep the dust suspended, but either way just trying to get the dust to the filter as quick as possible and get my sparkle back.
    12k IG salt; glass beads in plaster; K-2006C, K-1766, CCL, and Aussie 4in1 (HTH); Pentair Eco800 1.2HP VS; Zodiac SWC 1.3 lb/day (25 g/hr); 25" filter recycled glass; OKU solar panels; 1/2 HP solar pump; Rebel (Warrior) pool cleaner; FlowViz; prior pool AG 10k | Read Before Posting to get the best possible advice | ... and this helped me a lot!: TFPC for Beginners

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    Re: Affect of low CH with SWG?

    The cloudiness could be impurities in the salt. For example, if you added 200 lbs of 99.5% pure salt, half the impurities are soluble and half are not, there's around 1/2 pound of insoluble impurities floating around. I think you'd see that in the water, especially with the lights on.
    12k IG salt; glass beads in plaster; K-2006C, K-1766, CCL, and Aussie 4in1 (HTH); Pentair Eco800 1.2HP VS; Zodiac SWC 1.3 lb/day (25 g/hr); 25" filter recycled glass; OKU solar panels; 1/2 HP solar pump; Rebel (Warrior) pool cleaner; FlowViz; prior pool AG 10k | Read Before Posting to get the best possible advice | ... and this helped me a lot!: TFPC for Beginners

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    Re: Affect of low CH with SWG?

    I think you guys nailed it with the insoluble impurities . It was clear this morning...then I started up the Dolphin again it stirred up what was in the bottom and got a bit cloudy again. I'll keep the pump on today so the filter can work more. Thanks!


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    15' x 29' 10,300 gal w/ spa, IG-Plaster (Stonescapes Tropics Blue), 2spd WhisperFlo pump (1.5hp WFDS-26), Pentair Clean and Clear CC200 cartridge filter, Pentair MasterTemp 300BTU heater, Clear o3, RS-8 iAqualink

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    Re: Affect of low CH with SWG?

    Quote Originally Posted by ITR View Post
    I think you guys nailed it with the insoluble impurities . It was clear this morning...then I started up the Dolphin again it stirred up what was in the bottom and got a bit cloudy again. I'll keep the pump on today so the filter can work more. Thanks!


    Sent from my iPhone using Tapatalk
    You could try letting it settle again and then using a manual vacuum instead of the dolphin. Pushing a manual vacuum slowly around the pool will disturb the debris less.
    Matt
    16k IG PebbleTec pool, 650gal spa, spillway and waterfall, 3HP IntelliFlo VS / 1.5HP WhisperFlo, Pentair QuadDE-100 filter, IC40 SWCG, MasterTemp 400k BTU/hr NG heater, KreepyKrauly suction-side cleaner Dolphin S300i robot, EasyTouch controls, city water, K-1001, K-2006 and K-1766 test kits, Mannitol test for borates

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    Re: Affect of low CH with SWG?

    Thanks for the advice, unfortunately I don't have one of those. I just have the suction powered automatic that the PB left me a while ago and the Dolphin. I would assume the other one, since it bounces and has "fins" on it, would kick up even more.
    ----
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    Re: Affect of low CH with SWG?

    Okay..so I yanked the Dolphin and it was full of sand. Probably the dirtiest I have seen it. I have the filters soaking in dish soap now. Another question since I'm new to the SWG world (let me know if a new post would be more appropriate). I have been reading about people running their T-15 at 85-95% for 12+ hours. I went with the Jandy 40k AquaPure but if I recall, they have similar production (the Jandy is 1.25lbs/24 hours) I originally had mine on 85%, but it was over producing chlorine. Since I'm in central florida, the temps are in the mid 90s for a good part of daylight. I dropped it down to 25% production and run the pump on low for 3 hours in the morning and 3 hours in the evening and it has been keeping FC around 5 (CYA at 60). Knowing that the goal on PoolMath is 3-9, as long as FC is staying stable at 5...should I be concerned that I have it set at 25% for only six hours?
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    15' x 29' 10,300 gal w/ spa, IG-Plaster (Stonescapes Tropics Blue), 2spd WhisperFlo pump (1.5hp WFDS-26), Pentair Clean and Clear CC200 cartridge filter, Pentair MasterTemp 300BTU heater, Clear o3, RS-8 iAqualink

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    Re: Affect of low CH with SWG?

    That's great and no, don't be concerned at all. At 6 hours run time on 25% and a 10,300 gallon pool, you're producing 0.9 ppm FC per day.

    People on 12 hrs with an IC40 at 80% might have a 20,000 gal pool, little kids and teens in it day after day, and burn 3 or even 4 ppm FC per day.

    Most people talk about 2-3 ppm FC extinction per day. The lowest I've heard was 0.5 ppm per day. It varies widely depending on bather load, use of a cover, amount of sunshine, duck poo, etc. etc. etc.

    Don't worry. Be Happy
    12k IG salt; glass beads in plaster; K-2006C, K-1766, CCL, and Aussie 4in1 (HTH); Pentair Eco800 1.2HP VS; Zodiac SWC 1.3 lb/day (25 g/hr); 25" filter recycled glass; OKU solar panels; 1/2 HP solar pump; Rebel (Warrior) pool cleaner; FlowViz; prior pool AG 10k | Read Before Posting to get the best possible advice | ... and this helped me a lot!: TFPC for Beginners

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