TA extremely high - should I do something?

[skippydubois13]

Hi - new house with pool last year, and used your method with great success after daring to educate myself about chemicals and earning the nickname "The Chemist" at the now-boycotted pool store. (They got irritated with me when I actually wanted to know the chemical and function of lame-name products like "Water Polish," etc.)

My issue: opened my pool a week ago, much delayed due to ratty weather. Retracting electric cover revealed water in pretty nice condition - could see drain down 5.5 ft, just a few leaves and very fine debris. Started shock process and vacuuming. It just takes so long to get clear - I wind up shocking for two weeks because I don't stop until my water is pretty reasonably clear, and of course, my tests come out OK.

Historically, I have two main pool issues. 1) My fiberglass develops "tea stains", especially after shocking, which respond marvelously to your ascorbic acid advice, and 2) my water takes forever to clear, and is never as bright and sparkling as I remember our pool when I was a kid.

I've read TA isn't something to get too concerned with, but my numbers are WAY high, I think. I've been topping off the pool with water run through our Culligan water softener - thought this would help with mineral staining.

Using the tk test kit, here's the figures:

FC - 8 (it's rained - know I need to get back to 11)
CC - 1.0 (it's rained - tree dirt)
Ph - 7.2
CYA - less than 20 (treated last year, but I use maybe 6 3-in pucks a week for convenience, so figured it would migrate up on its own)
CH - 210
TA - 220

I have a plan to try a little DE in the filter, as so far this year, the pool has never been as clear as before I stirred up all the fine stuff on the bottom after I opened last week.

Do I need to act on this, avoid doing anything, or just wait out the filter? It's been a week and two days - water is basically as clear as when I started (but before I churned up the bottom.)

Thanks so very much for a consult!

 

[chem geek]

Welcome to TFP!

Since your pH isn't getting too high, don't worry about the TA until you've finished clearing your pool. The DE in the sand filter will likely help since it sounds like you've mostly got a circulation/filtration problem in terms of slow clearing.

You must not have a lot of sunlight on the pool; otherwise, the FC level would be dropping quickly during the day due to the low CYA level.

6 3" pucks (if 8-ounce weight) per week in 15,000 gallons would be 22 ppm FC (about 3 ppm FC per day) and 13 ppm CYA.

After your CYA gets up higher and you switch to using chlorinating liquid or bleach, then you may find that the higher TA has the pH rise too much in which case you can either just be diligent in adding acid frequently to keep the pH in range in which case the TA will slowly drop over time or you can accelerate the process by following the process of how to Lower Total Alkalinity.

Right now, your Calcite Saturation Index (CSI) is slightly below 0, mostly due to the lower pH, so that's fine. The cloudiness is probably not due to the high TA and even if your pH were to go to 7.5 it would likely not get cloudy (at 7.8 or 8.0, perhaps the water could get dull or you could have scale).

 

[skippydubois13]

Excellent. I won't sweat it. I worship at the shrine, Chem Geek. Thanks for the affirmation.

I will go through with the plan to add a little DE to kick up the filtration. You are quite right - the pool is half in shade, and we have had lousy weather with many more overcast days lately. This year, chlorine demand is nothing like in last year's hot and sunny summer.

Once I clear it up, my plan is stain free ascorbic acid + metal magic sequestrant to keep stains away. I've already treated with polyquat when I opened, so hopefully that goes well.

I will also keep a close eye on my pH. The ascorbic acid treatment last summer worked wonders - it might help my TA fall a bit, too.

 

[chem geek]

Just remember that the Polyquat 60 needs to be added weekly during the duration of time that you have the chlorine below normal (or at zero during the ascorbic acid treatment). It does not last forever and is not a one-time dose unless you are only having the chlorine be low or zero for less than a week.