It's because the higher salt levels have the CSI be lower but the CH recommended range isn't higher to compensate for that. I have long recommended that the CH range for SWG pools be higher, such as 350-450 and the pH range changed to 7.6-7.8, especially if one is using borates (to prevent scaling in the salt cell). See Saltwater Chlorine Generator (SWG) Recommended Levels for more info.
Bicarb Start-up
- Thread starter bdavis466
- Start date
Adding 24 pounds of calcium chloride would only raise the CH up about 60 ppm in your 33,000 gallon pool. So I don't know what is going on with your readings.
This seems to be exactly what I'm experiencing. So if it comes down to it, what do you recommend? My fill water is at least 8.2
High calcium with borates
Calcium within TFP guidelines and no borates
Higher TA with borates and calcium within TFP range
It was 28 pounds, my mistake. Could the extra calcium be from the plaster?
What about borates then?
Should my target for TA be 60? 80?
Will my CH rise on its own or do I need to add more calcium?
I am still suspect of my CH test. How can I check the accuracy? The R011L bottle is stained... Is that normal? I have used 3 different sources for the R0010 so I know that's not the issue.
Should my target for TA be 60? 80?
Will my CH rise on its own or do I need to add more calcium?
I am still suspect of my CH test. How can I check the accuracy? The R011L bottle is stained... Is that normal? I have used 3 different sources for the R0010 so I know that's not the issue.
When the indicator dyes go bad they start staining the plastic bottles. From your description, the R0011L is either starting to, or has completely gone bad.
There is no need to do anything with borates. Your current level is fine.
TA can stay where it is, or if you have very little aeration you could raise it a little.
CH tends to go up only if you have high CH fill water. Most people don't, but in Southern California you might well.
There is no need to do anything with borates. Your current level is fine.
TA can stay where it is, or if you have very little aeration you could raise it a little.
CH tends to go up only if you have high CH fill water. Most people don't, but in Southern California you might well.
I'll post a picture of the bottle when I get home. My kit is only two months old. Is that odd? If it is bad would it cause a lower reading?
I have a waterfall, spa and spillway. Aeration is unavoidable. I would prefer the TA to be lower but that may make more of an issue.
Per the water department, the hardness is anywhere between 90 and 200. I get 125 every time I've checked. I've heard people say it's as high as 400 but I've never seen that in my testing. The test shows my pool at 270-275 by both the 10ml and 25ml samples
I liked the idea of borates to slow the pH rise. I already purchased more than enough to get me to 50 but that was before I started looking at the CSI.
It seems to me that borates should not be recommended for swg pools because of this CSI issue.
I have a waterfall, spa and spillway. Aeration is unavoidable. I would prefer the TA to be lower but that may make more of an issue.
Per the water department, the hardness is anywhere between 90 and 200. I get 125 every time I've checked. I've heard people say it's as high as 400 but I've never seen that in my testing. The test shows my pool at 270-275 by both the 10ml and 25ml samples
I liked the idea of borates to slow the pH rise. I already purchased more than enough to get me to 50 but that was before I started looking at the CSI.
It seems to me that borates should not be recommended for swg pools because of this CSI issue.
No, the borates are most important to be used in an SWG pool because 1) they tend to have the largest pH rise, 2) helping to lower that pH rise needs a lower TA so the borates are supplemental pH buffering, and 3) the borates cut down the pH rise at the hydrogen gas generation plate roughly in half (in pH units) so significantly help prevent calcium carbonate scaling in the SWG cell.
The issue is not the borates nor the TA level. The issue is the pH and CH "recommended levels". There is no CSI issue if one balances all the parameters together properly. It's OK to target a slightly negative CSI for an SWG pool, but to do that with a lower TA and higher CYA (so even lower carbonate alkalinity which is what affects the CSI) one needs a higher pH and CH to compensate. Again, this is why I recommended a change to the Recommended Levels for SWG pools.
Thank you. Perhaps I'll shoot for 400 once I'm certain there is no issue with my calcium test.
As always, I am very thankful for all of the advice.
I was not aware of the post for revised levels in swg pools. Perhaps that should be a sticky or the recommended levels should be updated
As always, I am very thankful for all of the advice.
I was not aware of the post for revised levels in swg pools. Perhaps that should be a sticky or the recommended levels should be updated
Even with ph 7.6, ta at 60, salt at 3500, ch at 450, and 50 ppm borates, the CSI is 0.52. Isn't that way too low?
Did you perhaps mean negative 0.52?
I suggested PH at 7.7 minimum. That would give you a CSI of 0.42. But either way (-0.52 or -0.42) it is fine. There are two issues with CSI, what it is right this instant, and what it is likely to be tomorrow. Anything from -0.6 to +0.6 is fine right this instant. However some of your numbers will tend to change between now and tomorrow, and you need to take that into account as well. In practice CSI tends to go up fairly easily, assuming bleach/liquid chlorine/cal hypo/SWG, and almost never goes down on it's own, so something more like -0.6 to +0.3 is good. If you use trichlor/dichlor then PH tends to go down and the range would be -0.3 to +0.6 instead. Oh, and a SWG changes that a little more, because the CSI is way way higher inside the cell, so it is more like -0.6 to 0 that is ideal with a SWG.
I suggested PH at 7.7 minimum. That would give you a CSI of 0.42. But either way (-0.52 or -0.42) it is fine. There are two issues with CSI, what it is right this instant, and what it is likely to be tomorrow. Anything from -0.6 to +0.6 is fine right this instant. However some of your numbers will tend to change between now and tomorrow, and you need to take that into account as well. In practice CSI tends to go up fairly easily, assuming bleach/liquid chlorine/cal hypo/SWG, and almost never goes down on it's own, so something more like -0.6 to +0.3 is good. If you use trichlor/dichlor then PH tends to go down and the range would be -0.3 to +0.6 instead. Oh, and a SWG changes that a little more, because the CSI is way way higher inside the cell, so it is more like -0.6 to 0 that is ideal with a SWG.
I did mean negative 0.52. Sorry for the confusion.
I am using a swg. I don't see how the CSI would come up as long as I keep the values where they are now unless you are talking about a gradual CH rise and pH rise from the swg?
I am using a swg. I don't see how the CSI would come up as long as I keep the values where they are now unless you are talking about a gradual CH rise and pH rise from the swg?
PH rise from the SWG. You don't seem to have any right now, but it is very common and could occur at a later date (especially if you raise TA).
I was able to get the pH to 7.5 over night and I added 30 pounds of calcium to get me to 300. My plan is to let the pH rise to 7.8, get the CH to 350 and then add the boric acid. I'll try keeping the CH between 350 and 400 just to give me a little more of a margin on the CSI scale. I should be between -0.25 and -0.43 depending on where my pH chooses to want to stay.
I definitely think the recommended levels for swg pools should be revised so that someone who may not pay attention to the CSI doesn't end up in trouble and ultimately blame the current recommended methods for the damages caused.
Thanks again for the help. I'm looking forward to seeing how this works out.
I definitely think the recommended levels for swg pools should be revised so that someone who may not pay attention to the CSI doesn't end up in trouble and ultimately blame the current recommended methods for the damages caused.
Thanks again for the help. I'm looking forward to seeing how this works out.
I get -0.41 with PoolMath and -0.46 with my spreadsheet and those are on the low side of what would be OK. 350 ppm CH would be -0.52 with PoolMath and -0.56 with my spreadsheet. With ranges, the low end is always going to be low so the question is how low to keep things simple.
I would not say it's "way too low", but it is low. For quality plaster it tolerates a somewhat low CSI and the most important factor is to avoid low pH (onBalance did tank experiments that showed quality plaster coupons handling lower CSI until you got closer to the -0.7 to -1.0 range). Nevertheless, targeting something closer to 0 but below the level where you get scaling in the salt cell would be ideal. Probably something around -0.2 is a sweet spot and is the middle of what I was proposing for new recommended levels. It mostly comes down to how aggressive people are with a lower TA level to minimize pH rise. One compensates for that with a higher pH and CH.
You can see this post that goes into technical detail about the saturation index and plaster. Note that CSI is a logarithmic scale where -0.3 means that the product of calcium and carbonate concentrations is half that at full saturation, -0.6 would be one-fourth, -0.9 would be one-eighth.
I would not say it's "way too low", but it is low. For quality plaster it tolerates a somewhat low CSI and the most important factor is to avoid low pH (onBalance did tank experiments that showed quality plaster coupons handling lower CSI until you got closer to the -0.7 to -1.0 range). Nevertheless, targeting something closer to 0 but below the level where you get scaling in the salt cell would be ideal. Probably something around -0.2 is a sweet spot and is the middle of what I was proposing for new recommended levels. It mostly comes down to how aggressive people are with a lower TA level to minimize pH rise. One compensates for that with a higher pH and CH.
You can see this post that goes into technical detail about the saturation index and plaster. Note that CSI is a logarithmic scale where -0.3 means that the product of calcium and carbonate concentrations is half that at full saturation, -0.6 would be one-fourth, -0.9 would be one-eighth.
My TA is 70 now so that is probably the reason for the discrepancy.
With:
PH 7.8
Ch 350
Cya 80
TA 70
Salt 3500
50 ppm borates
I'm getting -.37. This is more than likely where I'm going to keep things. I am still in the process of getting everything into balance after the start up which is why some of the original numbers were pretty far off.
I was trying to get the TA down to 60 but now I see that it's not with it and it takes a long time to get the pH back up, not to mention the CSI is very low during that time.
I may go to 400 on the CH if it's that much of an improvement
With:
PH 7.8
Ch 350
Cya 80
TA 70
Salt 3500
50 ppm borates
I'm getting -.37. This is more than likely where I'm going to keep things. I am still in the process of getting everything into balance after the start up which is why some of the original numbers were pretty far off.
I was trying to get the TA down to 60 but now I see that it's not with it and it takes a long time to get the pH back up, not to mention the CSI is very low during that time.
I may go to 400 on the CH if it's that much of an improvement
You can just get your TA settled in to where your rate of pH rise is acceptable. Then you can raise the CH if you want. No sense raising it too soon since you might end up with a higher TA or pH target and not want your CH raised. pH and TA are easier to lower than CH.
I just thought I'd follow up on the entire process. I have really learned a great deal since the initial fill and given the chance to go through the process again, I would make a few changes.
The 500 -TA - CH formula works well for the initial amount of Bicarbonate to add but past that point, I'd just shoot for a CSI of +0.6-0.7. With as quickly as the pH rises from the TA being so elevated, I would want to limit any possible chance of scale (especially in brand new plaster). In my situation, this meant checking the TA and pH twice daily and adding nearly a gallon of acid (pH maintained between 7.8 and 8.0) per day. On average, my pH would rise 0.15- 0.25 per day, and that was with as little aeration as possible (I ran the spillway at a trickle with the air vent closed).
I now wish that I would have never added any calcium to the pool. I was so focused on getting the TA and CH into the RECOMMENDED levels that I added enough calcium chloride to get my CSI to -0.4 which at that time equated to 375 ppm. In hind sight, I would have kept the pH and TA higher (to compensate for the low CH) and adjusted both downward as the CH naturally rose. I would have also been much less aggressive in lowering the TA and allowed it to drop on its own with frequent acid additions.
My pool has a very large surface area in comparison to the volume of water it contains. That, coupled with high amounts of evaporation (84"/yr. per Chem Geek's post), my CH is rising at an alarming rate. My current CH is at 575 and i suspect it will be near 650 by the time things cool off. I might be able to make it one more year before I need to do a partial drain. Had I held off in adding the calcium and maintained a higher TA, I could have bought myself a little more time before a drain was required. I understand I would have had a higher acid consumption, but it really would have only been for a few months.
What I found surprising (after lowering the TA) is that my CSI was difficult to keep above -0.4 (TA 60-70) until my CH rose to 500 (I have a SW pool and use 50 ppm of borates), I now maintain a CSI between -0.3 and -0.1. Once the CSI reaches -0.1, I lower it to -0.35. Once it comes time to lower the CH, I will more than likely aim for no less than 450 ppm.
Lastly, I should have been adamant with my plaster contractor about not adding any calcium to the plaster mix. I was able to get him to drop the quantity in half, but even that was a fight. Calcium is used to shorten the time it takes to finish the plaster, but really all that it produces are color variations and a surface with areas that are noticeably rougher (set up too quickly). The additional calcium provides no benefit to the longevity of the plaster, and although I am unsure of it, I would imagine that the increased amounts of calcium in the plaster would be that much more detrimental to its integrity during an acid start up.
For the most part, the process was painless. I had no prior experience with water chemistry which leads me to believe if I could do it, then anyone can. The plaster is a considerable investment, why not take matters into your own hands to ensure its longevity?
The 500 -TA - CH formula works well for the initial amount of Bicarbonate to add but past that point, I'd just shoot for a CSI of +0.6-0.7. With as quickly as the pH rises from the TA being so elevated, I would want to limit any possible chance of scale (especially in brand new plaster). In my situation, this meant checking the TA and pH twice daily and adding nearly a gallon of acid (pH maintained between 7.8 and 8.0) per day. On average, my pH would rise 0.15- 0.25 per day, and that was with as little aeration as possible (I ran the spillway at a trickle with the air vent closed).
I now wish that I would have never added any calcium to the pool. I was so focused on getting the TA and CH into the RECOMMENDED levels that I added enough calcium chloride to get my CSI to -0.4 which at that time equated to 375 ppm. In hind sight, I would have kept the pH and TA higher (to compensate for the low CH) and adjusted both downward as the CH naturally rose. I would have also been much less aggressive in lowering the TA and allowed it to drop on its own with frequent acid additions.
My pool has a very large surface area in comparison to the volume of water it contains. That, coupled with high amounts of evaporation (84"/yr. per Chem Geek's post), my CH is rising at an alarming rate. My current CH is at 575 and i suspect it will be near 650 by the time things cool off. I might be able to make it one more year before I need to do a partial drain. Had I held off in adding the calcium and maintained a higher TA, I could have bought myself a little more time before a drain was required. I understand I would have had a higher acid consumption, but it really would have only been for a few months.
What I found surprising (after lowering the TA) is that my CSI was difficult to keep above -0.4 (TA 60-70) until my CH rose to 500 (I have a SW pool and use 50 ppm of borates), I now maintain a CSI between -0.3 and -0.1. Once the CSI reaches -0.1, I lower it to -0.35. Once it comes time to lower the CH, I will more than likely aim for no less than 450 ppm.
Lastly, I should have been adamant with my plaster contractor about not adding any calcium to the plaster mix. I was able to get him to drop the quantity in half, but even that was a fight. Calcium is used to shorten the time it takes to finish the plaster, but really all that it produces are color variations and a surface with areas that are noticeably rougher (set up too quickly). The additional calcium provides no benefit to the longevity of the plaster, and although I am unsure of it, I would imagine that the increased amounts of calcium in the plaster would be that much more detrimental to its integrity during an acid start up.
For the most part, the process was painless. I had no prior experience with water chemistry which leads me to believe if I could do it, then anyone can. The plaster is a considerable investment, why not take matters into your own hands to ensure its longevity?