When do CH and TA levels warrant adjusting?

[FlyAU98]

TF-100 Test kit...

CA stayed stable around 275 for most of the summer...its drifted down to 250 for the last month.
TA has dropped to around 65 (only a slight color change with the 7th drop of test reagent)

So I'm at the very bottom of the CH recommended level, and a little under TA.

TA is easy to pick up a small amount of baking soda, the calcium chloride...I've only seen larger quantities than I necessarily need of it (maybe 100oz).

Where do I REALLY want these numbers, and how often should I adjust them?

 

[JasonLion]

CH generally only needs to be adjusted once or twice a year. In many cases TA needs to be adjusted more often, depending on how much it tends to change.

When CH is at the low end of the range, it is best to keep TA in the upper half of it's range to balance things out. TA is easy to adjust, so that is the way I would go right now. Then worry about raising CH next season.

 

[FlyAU98]

I'm in South Florida...there is no "Next Season"!

 

[Smykowski]

The real answer is to keep CSI balanced.

Can you post a full set of results? Also, how does your pH behave? Is it relatively stable, or do you find yourself adjusting it often?

 

[FlyAU98]

FC=4 (I've been adding around 18oz of 10.5% every day or so)
CC=0
pH=8.2 (It drifts up slowly, we haven't been using the pool much, so had left it alone the past few weeks, usually about 16oz of Acid every couple weeks brings it right back to 7.5ish)
TA=65 (last adjusted to 90 (I was shooting for a little lower) in August, dropped to 80 in mid-sept, and 70 at the end of September and has stayed there since)
CH=250 (last adjusted to 275 in the middle of August. It stayed at 275 until early November)
CYA=50

Water temp is probably about 80 on average. It will probably drop a little this week. Its been cloudy, so the warm weather we have had, hasn't done much for the solar heat.

 

[JasonLion]

It is best to be careful to always keep the PH below 8.0.

 

[FlyAU98]

pH is back to 7.5...

 

[FlyAU98]

Ok, today's run of tests:

FC=8
CC=0
TC=8

pH=Between 7.5 and 7.8 (It was right at 7.5 before the baking soda)
TA=110 (it was 80, but added baking soda and retested)
CH=250 (tested twice, confirmed)

Water Temp is 81 degrees

Looking at pool math, my CSI is .03

Does that tell me that I still don't need to mess with increasing the calcium hardness, even though it remains at the bottom of the recommended levels?

 

[JasonLion]

Not really, it is simpler to ignore CSI and just stay within the recommended levels, which take CSI and a number of other factors into account. You will want to raise CH eventually, though that doesn't have to be right now, and by then the TA will probably have come down (TA of 110 is higher than we recommend unless you are using trichlor tablets).

 

[Richard320]

Just buy a couple one pound packets of Cal-hypo and use them instead of bleach to chlorinate. That'll raise CH.

 

[duraleigh]

+1 what Richard320 said.