Split off of this topic. JasonLion
Based on your numbers, to get a CSI of +0.12 your water temperature would need to be 58 F, is that correct?
One of the things you need to think about is how things will change as the water begins to warm up. If you use the same numbers at 88 F, then you get a CSI of 0.39. Here are some things that happen as the water warms up.
1) Carbon dioxide off gasses faster at higher water temperatures.
2) Warmer water has a higher CSI than cooler water for the same chemistry.
3) Warmer water means higher agitation and corresponding carbon dioxide loss and pH rise from increased usage
Therefore, while you are not having any trouble with a TA of 130 now, it will become more of an issue as the water temperature increases. Adding acid to keep the pH in the 7.5 to 7.6 range will cause the TA to steadily decline. This will help prevent problems as the water warms up. I think that a target of about 70 ppm for a water temperature of 88 F would do well.
Suggestion
Temp................TA
58...................130
68...................100
78.....................80
88.....................70
For adding borates, I recommend using boric acid rather than Borax and acid (Borax + acid = boric acid). For your 18,000 gallon pool, it will take 43 pounds of boric acid.
http://www.dudadiesel.com/choose_item.php?id=boric55
Based on your numbers, to get a CSI of +0.12 your water temperature would need to be 58 F, is that correct?
One of the things you need to think about is how things will change as the water begins to warm up. If you use the same numbers at 88 F, then you get a CSI of 0.39. Here are some things that happen as the water warms up.
1) Carbon dioxide off gasses faster at higher water temperatures.
2) Warmer water has a higher CSI than cooler water for the same chemistry.
3) Warmer water means higher agitation and corresponding carbon dioxide loss and pH rise from increased usage
Therefore, while you are not having any trouble with a TA of 130 now, it will become more of an issue as the water temperature increases. Adding acid to keep the pH in the 7.5 to 7.6 range will cause the TA to steadily decline. This will help prevent problems as the water warms up. I think that a target of about 70 ppm for a water temperature of 88 F would do well.
Suggestion
Temp................TA
58...................130
68...................100
78.....................80
88.....................70
For adding borates, I recommend using boric acid rather than Borax and acid (Borax + acid = boric acid). For your 18,000 gallon pool, it will take 43 pounds of boric acid.
http://www.dudadiesel.com/choose_item.php?id=boric55