TA turned blue

[mikkieblueeyes]

17600 gallon pool
IG
vinyl
sand pump

I used the pool calculator to determine the shock level for mustard algae that was floating in the pool this morning with these readings.

pH 7.2
FC 8.5
CYA 80 (we don't have a SWG and the pool is in full sun all day)
TA 300 (He wiped the tip of the bottle with a damp cloth inbetween drops)

I had him put in 5 bottles of 96oz. bleach according to the pool calculator.

After 1 1/2hrs I had him retest. It read:

pH 7.5 (the water returns are pointed to the surface of the pool still)
FC 22
CYA 80
TA (he stopped at 22 drops because the green was turning blue instead of red. He said he kept putting in more drops but it kept getting bluer)

So, please tell me what am I doing wrong?

My pool is still green and we can see maybe the 3rd step down and there are only 4 steps leading into the pool. After reading Pool School I've been going round and round. I don't understand because I read this site last year and had the pool all clear.

Thanks for any and all help!!!

 

[PaulR]

When the FC gets higher than 10, the pH test becomes unreliable.

High FC can affect the colors of the TA test. What's important is that the color changes and then stops changing, not exactly what color it is.

Adding bleach wouldn't affect the TA. Did you add acid also? Pointing the returns up suggests that you are trying to lower the TA as well. You should not try to lower TA and shock the pool at the same time because you won't get a reliable pH reading. Finish shocking first, then worry about the TA after.

Shocking means you bring your FC up to shock level (for CYA 85, that would be FC 33) and then maintain that level until the pool is clear, CC < 0.5, and you lose no more than 1ppm FC overnight.
--paulr

 

[Guest]

At very high FC the TA test will go from blue to yellow instead of green to red since one of the indicators bleaches out but the results are still valid. It's just jard to see the endpoint when it changes to yellow.

 

[sevver]

I test for TA alot, and I would swear that it goes to blue, at least blue-ish, before it goes to red. Usually it is within two or three drops of red at that point.

 

[Guest]

I test for TA alot, and I would swear that it goes to blue, at least blue-ish, before it goes to red. Usually it is within two or three drops of red at that point.

The transistion color is more of a dark greysish color to me (it's the transistion color from green to red and green and red neutralize each other.)

 

[Guest]

TA (he stopped at 22 drops because the green was turning blue instead of red. He said he kept putting in more drops but it kept getting bluer)

So, please tell me what am I doing wrong?

It is very possible that your TA is higher than 220 ppm. You can do a lower resolution test by using a 10 ml sample, adding one drop of the first reagent and three drops of the indicator. Then every drop of titrant is equal to 25 ppm of TA. Remember to swirl the vial between drops for about 5-10 seconds to insure the reagent is mixed thoroughly.

 

[mikkieblueeyes]

Thanks for everyone's help. I read over this website last year and had my pool very clear but didn't take notes so this year when I started I was confused all over again about which test to do first.