Alkalinity wont come down

[rltullis]

i have been to pool store 3 times. each time they say 2 pounds of dry acid. we add and no change or if anything it goes up.
here is where i am i am not good on pool chemistry so maybe someone can point out something i am not seeing

FC -2
Available Chlorine - 2
Salt - 2600
calcium -240
cya - 50
TA - 430
PH - 8.0
acid demand - 6
no metals in water all else is good

i have a 17000 gallon fiberglass pool on a sand filter with a salt water generator.

please help what am i doing wrong.

 

[mas985]

Are you sure TA is that high?

What is CH?

Start here: Pool School - ABCs of Pool Water Chemistry

Then here: Pool School - Lower Total Alkalinity

 

[Richard320]

The big problem i see is right here: "i have been to pool store 3 times"

If (A big if) those numbers are right... it'll take 16 pounds of dry acid just to get pH down to 7.2. That will have the added benefit of reducing TA by... 43. And then over time (assuming no fresh fill water was added) the pH will rise to 7.8 or so and TA will be at 287 so another 13 pounds of dry acid, which will reduce TA by another 34. It'll take a long long time and cost a whole lot of money.

On the other hand, if you had your own test results in hand and used Muriatic Acid, you could devote a weekend to driving TA down. It will still be in those same steps and it will use a lot of acid, but MA from a big box hardware store has got to be cheaper than dry acid from the pool store and you'll save a lot of trips back and forth. And you'll be in control, not the clerk at the pool store with dollar signs in his eyes.

And also, your Free Chlorine is too low for your CYA level. Pool School - Chlorine / CYA Chart

 

[rltullis]

i have tested TA myself and while my measurements are not super accurate they are close to those of the pool store.

chlorine is 2.0

- - - Updated - - -

calcium hardness is 240

- - - Updated - - -

The big problem i see is right here: "i have been to pool store 3 times"

If (A big if) those numbers are right... it'll take 16 pounds of dry acid just to get pH down to 7.2. That will have the added benefit of reducing TA by... 43. And then over time (assuming no fresh fill water was added) the pH will rise to 7.8 or so and TA will be at 287 so another 13 pounds of dry acid, which will reduce TA by another 34. It'll take a long long time and cost a whole lot of money.

On the other hand, if you had your own test results in hand and used Muriatic Acid, you could devote a weekend to driving TA down. It will still be in those same steps and it will use a lot of acid, but MA from a big box hardware store has got to be cheaper than dry acid from the pool store and you'll save a lot of trips back and forth. And you'll be in control, not the clerk at the pool store with dollar signs in his eyes.

And also, your Free Chlorine is too low for your CYA level. Pool School - Chlorine / CYA Chart

why does the pool store keep telling me 2 pounds when it needs 16? is their system nuts?

i am fine with muriatic but have been told not to put in my fiberglass pool i think i could get away with a bit but seems this much would be an issue or not?

 

[Richard320]

i have tested TA myself and while my measurements are not super accurate they are close to those of the pool store.

chlorine is 2.0

- - - Updated - - -

calcium hardness is 240

- - - Updated - - -



why does the pool store keep telling me 2 pounds when it needs 16? is their system nuts?

i am fine with muriatic but have been told not to put in my fiberglass pool i think i could get away with a bit but seems this much would be an issue or not?

You mix the powder with water and end up with liquid acid before you add, correct? Otherwise you might end up with acid crystals leaving freckles on the pool surface. Why not skip a step and just add liquid acid? Thousands and thousands of TFP members use MA in fiberglass and vinyl with no problems. I suspect pool stores prefer to sell dry acid because it's easier to handle. (For them)

 

[kimkats]

I bet it costs more also so more $$ for them!

Kim:cat:

 

[rltullis]

so how much muriatic acid are we talking about here to get this where it needs to be? also how in the world did it get this high? I just opened the pool, have not done much other than clean it out.

 

[Richard320]

so how much muriatic acid are we talking about here to get this where it needs to be? also how in the world did it get this high? I just opened the pool, have not done much other than clean it out.

Gallons and gallons.

High TA can come from fill water, someone adding too much Baking Soda, or testing errors.

 

[rltullis]

i have been told by several folks that our local water is being treated differently this year. maybe that is the cause.

 

[kimkats]

I would do a test on your fill water just to see what you have ahead of you.

Kim:cat: