how did i screw up my TA so badly?

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crackers8199

Bronze Supporter
Jun 5, 2014
288
Lake Elsinore, CA
i've been watching my TA drop steadily over the past few months, and for each of the past 3 weeks when i did my weekly tests i had it at 50 each time. so, i figured i'd add a tiny bit of baking soda to try to bring it up. earlier this week, i turned off my SWCG for the winter, so i added some liquid chlorine yesterday and then also went about adding baking soda.

pool math says 23 oz to bring it up from 50 to 60 for a 10k gallon pool (which is roughly what mine is). so, to try to start small, i went a little below the recommendation. i measured out 20 oz by weight of baking soda and dropped it around the deep end of the pool and then brushed to mix it all around.

today, i did another set of weekly tests to see where i was at...and i noticed my pH had jumped (after being extremely stable in the mid 7s for the past week or so since turning the SWCG off, it jumped to 8.0). then i did a TA test...it's now measuring at 120. i've already added acid and have the waterfall running to try to bring it back down, but i don't understand how i launched it into the stratosphere like this. i added less than what pool math even said to add.

how the heck did i screw this up so badly? what did i do wrong? the only thing i can think of is that i just switched to a new bottle of the third reagent for the TA test, and maybe the old one was past expiration (although i didn't see a date on the bottle)...but even then, would that skew the numbers so badly?
 
What you did wrong was tinkering with your water chemistry too much. If your pH is stable then leave your pH and TA alone.

TA 50 with a stable pH was just fine and more towards equilibrium.

A TA of 120 is ok, especially in the winter with your SWG off. Don't focus on your TA. Just keep your pH between 7.6 and 8, more towards 8 and let your TA be whatever it wants. Doing less will be better for your pool. Find something else to do with your free time.
 
ajw22 said:
What you did wrong was tinkering with your water chemistry too much. If your pH is stable then leave your pH and TA alone.

TA 50 with a stable pH was just fine and more towards equilibrium.

A TA of 120 is ok, especially in the winter with your SWG off. Don't focus on your TA. Just keep your pH between 7.6 and 8, more towards 8 and let your TA be whatever it wants. Doing less will be better for your pool.
Click to expand...

that's fair, but i still don't understand how i added less than what pool math told me to add and somehow launched the TA into orbit. i was tinkering because i have extreme scaling issues, so i try very hard to keep the CSI negative. in the past, my pool has liked to have TA around 60 or 70, so watching it drop to 50 and stay there for a few weeks was setting off alarm bells for me. this is the first time i've added baking soda to the pool in probably a year and a half.
 
crackers8199 said:
my pool has liked to have TA around 60 or 70, so watching it drop to 50 and stay there for a few weeks was setting off alarm bells for me.
Click to expand...

Why alarm bells if your TA is 50?

What do you think is bad about your pool being at TA 50? TA 50 lowers your CSI further which more achieves your objective.
 
aussieta said:
make sure to wipe the tip on the ta reagent with a damp cloth between drops
i would think static electricity is your problem
your maths seems correct
measure out another 20oz and compare to your memory of what you added
1.25lbs
Click to expand...

i used a food scale to weigh it, so i'm 100% sure the 20 oz by weight was the exact amount i added. i scooped it from a 15 lb bag into a plastic cup that was sitting on the scale tare'd to zero before i started, then dumped from the cup into the pool.
 
crackers8199 said:
probably just my own paranoia. in the year and a half since i started doing my own testing, i've never seen it get that low...so my brain told me to try to bump it up a tiny bit.
Click to expand...

Learn more about TA here...

TA - Further Reading

www.troublefreepool.com www.troublefreepool.com
 
ajw22 said:
Learn more about TA here...

TA - Further Reading

www.troublefreepool.com www.troublefreepool.com
Click to expand...

yes, i've read all of that many times. somehow i missed the part that 50 was an acceptable minimum. i knew 60-80 was ideal, but i saw 50 and my brain said "that's not ideal! too low, bump it up!" ugh.

regardless of my screw up there, i still don't understand how adding less baking soda than pool math said should take me up by 10 points somehow launched me up by 70 points. i get that i shouldn't have messed with it, that's on me...but how did the pool math calculator numbers given to me change the actual TA by such a wide margin vs what it should have done? there's no way that adding 20 oz of baking soda should increase TA from 50 to 120 in a 10k gallon pool...right?
 
crackers8199 said:
there's no way that adding 20 oz of baking soda should increase TA from 50 to 120 in a 10k gallon pool...right?
Click to expand...

Chemistry is not always that precise. And PoolMath calculations are not always perfect. Chemicals are not always as pure as you want. Lots of ways errors creep into your chemistry.

Is your pool exactly 10K gallons?

A small error has less of an effect in a large pool like my 35K pool then in your smaller pool.

In 30 years of having a pool I have never needed to add baking soda and adjust my TA. Manage your pH and let your TA be whatever it wants to be.
 
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ajw22 said:
Chemistry is not always that precise. And PoolMath calculations are not always perfect. Chemicals are not always as pure as you want. Lots of ways errors creep into your chemistry.

Is your pool exactly 10K gallons?

A small error has less of an effect in a large pool like my 35K pool then in your smaller pool.

In 30 years of having a pool I have never needed to add baking soda and adjust my TA. Manage your pH and let your TA be whatever it wants to be.
Click to expand...

that's also fair. i was just shocked to see such a large variation.
 
aussieta said:
make sure to wipe the tip on the ta reagent with a damp cloth between drops
i would think static electricity is your problem
Click to expand...
Ensure that you did this. The static can cause your reagent drops to be smaller and cause a much higher reading.

--Jeff
 
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Turbo1Ton said:
Ensure that you did this. The static can cause your reagent drops to be smaller and cause a much higher reading.

--Jeff
Click to expand...

If he was testing at CYA 50 and did not start a new reagent bottle then the reagents would not suddenly get static electricity and test high.
 
ajw22 said:
If he was testing at CYA 50 and did not start a new reagent bottle then the reagents would not suddenly get static electricity and test high.
Click to expand...

the new bottle was started today with the higher test. last test at 50 was the last test with the old bottle.

i'll go outside right now and run another test and wipe the bottle to see if it changes the result. will report back in a few minutes.
 
Turbo1Ton said:
Ensure that you did this. The static can cause your reagent drops to be smaller and cause a much higher reading.

--Jeff
Click to expand...

seems this was the culprit. ran another test (keeping in mind i did just add acid to bring the pH down from 8 to 7 when i thought i needed to knock the TA down before this post even came about)...wiped the tip of each of the TA reagents both to start and between each drop. TA now measures 70...which is still higher than where i would have expected it to be, but not insane like the 120 reading I got earlier today.

thanks for helping me figure this out!
 
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