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Thread: Csi

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    mvk111's Avatar
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    Csi

    My csi index is showing as 0.11 is this decent?

    Below are my numbers from when I just tested.

    Fc 4
    Cc 0
    Tc 0
    Ph 7.5
    T/A 100
    Ch 210
    Cya 70

    Added bleach to get fc up to 7ppm, and going to add some (140 oz)calcium chloride to get ch to 300. These numbers ok?
    15x30 free form (10,500 gal) SWG
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    Mod Squad Bama Rambler's Avatar
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    Re: Csi

    As long as your numbers are in the recommended ranges suggested here I wouldn't worry about your CSI.

    What's your temp and salt numbers. I don't get anywhere near .11
    Dave J. TFP Moderator
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    Re: Csi

    I can look at your test results and see they are within ranges we use here on the forum. As a result, CSI is virtually irrelevant and always will be as long as you stay within those guidelines.

    CSI is a bit of sore spot with me as it is almost completely unnecessary. I know others will post back and point out times when it can be helpful but, it seems to me, those times are so infrequent they are hardly worth mentioning.

    I have never calculated CSI for my pool and don't see that I will really ever have a need.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
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    Re: Csi

    Thanks guys...temp is 83 and we have not turned on the swg yet.
    15x30 free form (10,500 gal) SWG
    Gunite, Game depth 3.5-5-4 ft, 1 hp Sta-Rite Super Max 2 speed pump, 53' Sta-Rite system 3 DE filter
    Pentair Intellibrite LED
    Pentair 125k BTU ultra temp heat pump,
    Screen Enclosure
    TF-100 Test Kit

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    Re: Csi

    Quote Originally Posted by mvk111
    My csi index is showing as 0.11 is this decent?

    Ph 7.5
    T/A 100
    Ch 210
    Cya 70
    You might have made a mistake with the calculator. Using the following:

    pH = 7.5
    TA = 100
    CH = 210
    CYA = 70
    Salt = 3200
    Temp = 83 F

    I get a CSI of -0.36.

    http://www.poolcalculator.com/

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    Re: Csi

    Quote Originally Posted by duraleigh
    I can look at your test results and see they are within ranges we use here on the forum. As a result, CSI is virtually irrelevant and always will be as long as you stay within those guidelines.

    CSI is a bit of sore spot with me as it is almost completely unnecessary. I know others will post back and point out times when it can be helpful but, it seems to me, those times are so infrequent they are hardly worth mentioning.

    I have never calculated CSI for my pool and don't see that I will really ever have a need.
    I agree. During the first 4 months or so after construction I religiously followed the CSI and always stayed within the "balanced" range. Yet when my CH went over 600 and my CSI never approached .4 I still developed some discoloration of my plaster. I suppose you could say that CSI works when you are within the recommended ranges, but then what's the point of having a separate scale to tell you that the pool is balanced when it's already apparent? Or perhaps the rule is that CSI works unless you have high CH?
    9,200 gal. Gunite Luna Quartz French Grey pool with spill over spa, two fountains on tanning ledge (rarely used)
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    Re: Csi

    Quote Originally Posted by HouTex
    I agree. During the first 4 months or so after construction I religiously followed the CSI and always stayed within the "balanced" range. Yet when my CH went over 600 and my CSI never approached .4 I still developed some discoloration of my plaster. I suppose you could say that CSI works when you are within the recommended ranges, but then what's the point of having a separate scale to tell you that the pool is balanced when it's already apparent? Or perhaps the rule is that CSI works unless you have high CH?
    That isn't my recollection. According to your posts here, here and here, your pH was 8.0 to 8.2 for perhaps one every four days. The CH varies from 440 to 675 (and later to 800). You do mention in this post about the CSI being balanced but in this post you mention how the pH gets up to 7.8 to 8.2 in a few days.

    With fill water that has 200+ TA and CH of 150 (is that from the pool store or your own testing?), it is a challenge to keep your pH from rising. Using numbers from this post (and using temp of 89 from this post), the CSI will vary from around -0.3 at a pH of 7.2 to +0.4 at a pH of 8.0 and +0.6 at a pH of 8.2. When your CH was at 800 the index would have been +0.2 higher.

    The problem isn't with the CSI but with the definition of "balanced" being the broad +/- 0.6 in the pool calculator. The industry usually uses +/-0.3, but in reality the number just tells you what is possible, not what will happen with any certainty. In practice, we usually don't see scaling in pools until the index gets to around +0.7 but I've seen reports of scaling in spas at around +0.3 to +0.4. Your pool finish is different than others and given that it is newer and was apparently still curing, the pH at its surface will be higher than in the bulk pool water so scaling will be much more likely at lower bulk water CSI than in a pool where the plaster is more fully cured. This same principle explains why there can still be calcium flaking in a saltwater chlorine generator cell when the bulk pool water has a zero or negative CSI -- the pH at the cathode (hydrogen gas generation plate) is much higher than in the bulk pool water. However, even under these conditions, the lower the CSI the less scale there will be (there is also another measurement called the Calcium Carbonate Precipitation Index to determine the amount of scale possible, but that's another subject that I briefly mentioned in one of your threads here).

    As for ranges vs. CSI, I suppose one could consider your pH getting to 8.0 and above to be out of range and just attribute your scaling to that for simplicity, but if your CH or TA were much lower then that would not have been a problem (except for potential metal staining). Also, for some pools and most certainly for spas one sometimes sees the TA get lowered significantly below 70 ppm, even to 40-50 ppm, so in that case how can one go by standard ranges and think everything is OK? If one gets that low in TA and has a plaster surface, then the CH should be raised significantly and perhaps a higher pH target of 7.7 to 7.8 be used. One could only figure that out based on the CSI, not based on looking at ranges alone.
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    Re: Csi

    I'm pretty sure my CH never approached 800. True, I did get that result with my TF-100, but that was before getting a SpeedStir. After using the SpeedStir the highest reading for CH was 675--still too high (and I've since lowered it), but that meant that the most my CSI ever hit was .42 at pH of 8.2--and this was for a very short period. IIRC, I saw several posts on the forum that said a CSI at that level would not cause scaling. [edit] Here is one thread I found that suggests that scaling is rare below .7. spot-etching-and-csi-t29640.html?hilit=CSI scaling

    I test pH every day (and at the time of some of my previous posts twice a day) and whenever it became dark red but not purple (7.8, 7.9, 8.0?) I added MA. Re-reading my old posts and thinking back about my test results I don't ever recall reaching the purple stage of 8.2--and if it did it was not for very long and possibly only over night. Typically, and to the best of my memory, pH would have maxed out (and for a short time only) at 8.0 and that would have given me a CSI of .21 which The Pool Calculator says is balanced. I would have immediately added MA to bring it down to 7.2.

    Now, I continue to test my water every day and typically have to add MA every other day and make sure pH never exceeds 7.8. The problem is the Texas drought and keeping my TA in the 50-70 range considering I have fill water with TA of 250.
    9,200 gal. Gunite Luna Quartz French Grey pool with spill over spa, two fountains on tanning ledge (rarely used)
    Pentair Whisperflo 2HP, Pentair CCP Cartridge 420 Sq. Ft., Polaris 280 with booster pump
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    Need help

    I gotta crazy question..you can see my test numbers above that I took yesterday. I added 70 oz of calcium hardness just to see where that put me then I was going to add the other 70 oz or so. I tested my FC just now and it was zero !!!! It was full sun all day today and yesterday...but where did my chlorine go ????? Did in eat up 7ppm of FC since yesterday afternoon or did adding 70 oz of calcium chloride eat it up....please help me figure out what occurred...I just freaked out when FC test was clear....I just added 152 oz to get me back up to 7ppm....should I be fine since I caught it quick and where did it all go since yesterday? Pool is crystal clear right now. Thanks
    15x30 free form (10,500 gal) SWG
    Gunite, Game depth 3.5-5-4 ft, 1 hp Sta-Rite Super Max 2 speed pump, 53' Sta-Rite system 3 DE filter
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    Re: Csi

    Only two things consume chlorine.....the Sun and organic material in your pool. On most balanced pool, a loss of 2-3ppm DAILY to the sun is common. That could account for it or you could have algae developing in your pool that is consuming some as well.

    Check out "ABC's of Pool Water Chemistry" in Pool School.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Re: Csi

    Quote Originally Posted by duraleigh
    Only two things consume chlorine.....the Sun and organic material in your pool. On most balanced pool, a loss of 2-3ppm DAILY to the sun is common. That could account for it or you could have algae developing in your pool that is consuming some as well.

    Check out "ABC's of Pool Water Chemistry" in Pool School.
    Ok thanks....very new to this, I tested 4 ppm Sunday morning and 0 Monday night so that would make sense if it consumes 2-3ppm a day, that would have been two days I guess....I will start keeping a tighter eye on it till I get a better feel of what it consumes and it's characteristics...
    15x30 free form (10,500 gal) SWG
    Gunite, Game depth 3.5-5-4 ft, 1 hp Sta-Rite Super Max 2 speed pump, 53' Sta-Rite system 3 DE filter
    Pentair Intellibrite LED
    Pentair 125k BTU ultra temp heat pump,
    Screen Enclosure
    TF-100 Test Kit

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