How concerned should I be with TA and CH

[IL_WS]

Recent numbers:
FC = 6.0
CC = 0.0
PH = 7.5
CYA ~ 42 (much closer to 40 than to 50)
TA = 170
CH = 40

The CYA number is from opening the pool, and is probably diluted some with some very heavy downpours we had several weeks ago. However, that would really just drive me to maintain lower FC since I do not seem to be burning it much (keep the solar cover on unless swimming).

However, what should I be concerned with concerning high TA (SimplePool recommends 70 to 90+), and low CH (SimplePool recommends 50 to 300)?

 

[Richard320]

Your vinyl pool doesn't care about CH levels. Ignore it.

If everything else is good and the pH is fairly stable, ignore the TA. Whether you aggressively try to lower it or just keep adding acid when the pH climbs, it will take the same amount of acid, just over a longer period of time.

 

[Bama Rambler]

With an above ground pool don't even pay the CH any attention. Completely ignore it.

With your TA that high I'm surprised that you aren't having to fight the pH. Regardless, don't worry about it. Just keep the pH adjusted whenever it needs it and let the TA take care of itself.

 

[IL_WS]

Your comments have me concerned about the accuracy of my pH measurements.

Last season, I had to add acid every few days to keep it low enough. I do not remember if this was right after using pucks, or after I switched to BBB.

This season, I started at 7.8, and have been around 7.5 for 2 months now. I have not needed to add anything to adjust.

I do not have any water features, other than occasionally pointing the return jet upward for kids to play in it. I do not have a SWG. I have been running my pump about 5 hours a day for at least a month now.

I am testing pH with the dropper that came with the TF100 kit. I bought it last year, and stored indoors over the winter. What life expectancy can I expect on the reagents (specifically for pH, but extended to all of them).



Also, looking again at the test kit description here, it says the OTO total chlorine is useful for daily chlorine testing. I have been doing the FAS-DPD test for regular tests. Is OTO TC adequate?

 

[Bama Rambler]

I always use the FAS-DPD for chlorine. and I'll use the OTO as a go/no-go test for chlorine.

You should get a couple of years out of the reagents for any of the tests if you store them indoors. I would suspect the TA test before I would the pH one. Either way I wouldn't worry about it.

 

[IL_WS]

If everything else is good and the pH is fairly stable, ignore the TA. Whether you aggressively try to lower it or just keep adding acid when the pH climbs, it will take the same amount of acid, just over a longer period of time.

Coming back to this. My pH has continued to decrease slowly over time (7.2 now) without any intervention on my part. I have only added bleach this season. I have been aerating only when we are in the pool (cover off) by redirecting the outlet eyelet. I am concerned with adding baking soda to increase pH because I think it will tend to lock the high TA in place.

 

[Bama Rambler]

You have a TA of 170 ppm and your pH keeps falling?

What is your TA now?

 

[linen]

bama beat me, here are my thoughts:

I am concerned with adding baking soda to increase pH because I think it will tend to lock the high TA in place.

Baking soda has very little effect on ph, it mostly adjusts TA up. If you need to adjust ph up, use aeration or Borax.

What is your TA now?

Any chance you have an autofill?

What is your fill water ph and TA?

 

[IL_WS]

You have a TA of 170 ppm and your pH keeps falling?

What is your TA now?

I don't have my latest TA numbers from a month ago with me, but I will retest tonight or tomorrow. Before retesting, I will have my wife babysit me on following the directions to help remove operator error on my part.

But you are right. I have had high TA all season (June - now), and my pH has crept slowly from about 7.8 to 7.2.

And linen is right that I meant Borax and not baking soda. Pool calculator told me that, but I misremembered when I typed it out. And I do not have autofill. I added about 20% water at the start of season, a few inches in the heat of summer, and whatever rain water God provided.

 

[IL_WS]

What is your TA now?

Results from Saturday are:

• TA=140
  pH=7.2 (or a touch lower)

For the entire season, TA has been between 170 and 140, and pH has dropped slowly from 7.8 to now 7.2. I will be closing the pool in a few weeks (Chicago nights are driving the daily average near 60).

• Should I adjust pH before then?
  Should I try to adjust the TA (aeration, acid repeat)?

 

[linen]

Just to check, we are assuming you are not using trichlor or dichlor (chlorine granuals)?

Did you measure your fill water TA, and ph?

 

[IL_WS]

Just to check, we are assuming you are not using trichlor or dichlor (chlorine granuals)?

Did you measure your fill water TA, and ph?

I am using 12.5% bleach for chlorination this entire season. Last year (new pool) when I was using pucks (trichlor I think), pH was constantly rising and I adjusted with acid.

I have not tested the fill water TA or pH. I will try to remember to do that tonight.

Beyond springtime with about 20% addition, I have not added any significant level of tap water (mostly drain from rain).

 

[jblizzle]

How is your pH behaving opposite of the rest of the world's pools?

Pucks are acidic, so that should have resulted in your pH dropping last year all the time. While this year, we would have expected stable or rising pH. Unless your source water has drastically changed characteristics.

 

[linen]

I am using 12.5% bleach for chlorination this entire season. Last year (new pool) when I was using pucks (trichlor I think), pH was constantly rising and I adjusted with acid.

This has me stumped...trichlor should have lowered your ph, but it didn't, instead it went up. Using bleach/LC should have only added to the upward drift in ph. I agree with jbliz, I think we are missing something here...but I don't know what.

 

[IL_WS]

How is your pH behaving opposite of the rest of the world's pools?

Pucks are acidic, so that should have resulted in your pH dropping last year all the time. While this year, we would have expected stable or rising pH. Unless your source water has drastically changed characteristics.

I am also stumped now that I realize that what I am seeing is opposite what is expected. Expectations never stuck in my mind last year as I was studying this stuff, I just treated the results. Should I continue to treat the results (low pH), or suspect my test kit?