question about alk level

[LazyLgrecian]

I've been using the BBB method for 3 years now without problems, thank-you poolforum. I got a call yesterday from a friend who didn't follow my advice to use the BBB method , nor did he use the free kit i assembled for hism a year ago. So I went over to his pool to see what he's got going on. He's been using alot of shock powder when ever he had an algae flare up along with some pucks. and no testing. So his ph was off the scale low, no surprise there, and his cya level is about 120 to 140 kinda hard to guess with anything over 100. my question is about his TA level. the test sample never turned green but turned red with the addition of the second chemical. Should turn green then red after adding the 3rd chemical. I don't remember trichlor powder, affects TA levels. Does it make it go up or down. I don't want to tell him to add Baking Soda unless I'm sure that's what he needs to do. I used to a paper with how and what amounts a gallon of 6% bleach, a pound of trichlor and a pound of dichlor had on 10K gallons of water , for ph cya and TA. is that table still here somewhere?

TIA
Michael

[waterbear]

If the pH is low then the TA could very possibly be 0 ppm and the indicator will turn red immediately. Trichlor is acidic and eats up TA over time and causes the pH to crash.
TA is the measure of bicarbonates in the water.
When the pH is very low the bicarbonates have been converted into carbonic acid and therefore not measurable by the TA test. Effectively, there is no carbonate alkalinity in the water since it is all in acid form.

[aylad]

Originally Posted by LazyLgrecian

I used to a paper with how and what amounts a gallon of 6% bleach, a pound of trichlor and a pound of dichlor had on 10K gallons of water , for ph cya and TA. is that table still here somewhere?

I'm not sure that I ever saw that table, but I can tell you that one gallon of 6% bleach will provide 6 ppm Chlorine in 10 gallons of water. I also can tell you that for about every 10 ppm chlorine obtained with trichlor, you raise your CYA by about 5 ppm. Trichlor will drop your TA and pH, but how much it drops your pH depends on your alk level. I've never used dichlor so I can't advise you about that, but I do believe that dichlor isn't quite as acidic as the trichlor is.

Janet

[waterbear]

Dichlor is less acidic than trichlor but the net results are still acidic and for every 10 ppm fc added it will add 9 ppm CYA.