TA test - record fully pink/red or just partially pink/red?

Problems relating to pH and total alkalinity.
Increase ph, increase TA. Reduce pH, reduce TA.
pH chemistry advice and techniques for the pool.
Henry_R
Swimming Pool Pro
Swimming Pool Pro
Posts: 126
Joined: Fri 20 Mar, 2009 21:41
My Pool: HOA Community Swimming pool built approx. 1971.
In-Ground, Plaster 34x18 3.5-6' deep, Sta-rite P2R A5D-120L pump, A.O. Smith centurion 1HP (uprated 1.25HP) motor,Hayward S244S filter(new 2011), Rainbow Lifegard Chlorine/Bomine feeder; new replastered June 2010
Location: Houston, Texas USA

TA test - record fully pink/red or just partially pink/red?

Postby Henry_R » Sun 28 Aug, 2011 10:00

When doing the Total Alkalinity test are you supposed to record the amount when the color first goes a little pink/red or when it turns fully pink/red? I've done the test and I'll get to like 13 or 14 drops and it just starts to get red then on the 15th drop it turns bright. When do I stop at the first sign of red/pink or until it's bright red?
I've been doing the latter which is usually only one drop more but I want to be sure I'm doing that right since it's a higher reading.


Money talks!? All it ever says to me is "goodbye!".
chem geek
Pool Industry Leader
Pool Industry Leader
Posts: 2382
Joined: Thu 21 Jun, 2007 21:27
Location: San Rafael, California

TA test - record fully pink/red or just partially pink/red?

Postby chem geek » Wed 31 Aug, 2011 20:35

It's technically the last drop that produces a color change. If you add another drop and don't see a change, then don't count that last drop. If you add a drop and it goes from green to a gray or starting to be red, keep going (probably one more drop). So in your case, count it with the higher number.

In practice, it doesn't matter very much since you don't really have to be within 10 ppm and the effect on the saturation index isn't that much unless your TA is very low. Remember that you generally aren't shooting for a particular TA target, but rather getting the TA to a level where the pH is reasonable stable. If the pH tends to rise, then lower the TA. If the pH tends to fall, then raise the TA. If you lower the TA such that you make the saturation index negative, you can compensate by increasing CH as well as your pH target (say, 7.7 instead of 7.5).
Henry_R
Swimming Pool Pro
Swimming Pool Pro
Posts: 126
Joined: Fri 20 Mar, 2009 21:41
My Pool: HOA Community Swimming pool built approx. 1971.
In-Ground, Plaster 34x18 3.5-6' deep, Sta-rite P2R A5D-120L pump, A.O. Smith centurion 1HP (uprated 1.25HP) motor,Hayward S244S filter(new 2011), Rainbow Lifegard Chlorine/Bomine feeder; new replastered June 2010
Location: Houston, Texas USA

TA test - record fully pink/red or just partially pink/red?

Postby Henry_R » Fri 02 Sep, 2011 08:31

chem geek wrote:It's technically the last drop that produces a color change. If you add another drop and don't see a change, then don't count that last drop. If you add a drop and it goes from green to a gray or starting to be red, keep going (probably one more drop). So in your case, count it with the higher number.

In practice, it doesn't matter very much since you don't really have to be within 10 ppm and the effect on the saturation index isn't that much unless your TA is very low. Remember that you generally aren't shooting for a particular TA target, but rather getting the TA to a level where the pH is reasonable stable. If the pH tends to rise, then lower the TA. If the pH tends to fall, then raise the TA. If you lower the TA such that you make the saturation index negative, you can compensate by increasing CH as well as your pH target (say, 7.7 instead of 7.5).
OK. Then I'm doing it right. Good. Now to convince some laypersons of the need for more MA since TA keeps going up and taking pH with it. We have just over a quart of MA left and the acid demand chart of the Taylor Basic kit and the pool calculator agree on the need of 1.6 quarts to bring pH from 8.2 to 7.5.
Since I really want to go lower than that as you've said I need more MA.

I cannot do anything until Monday though. People will want to swim over the weekend so I have to confine water adjustments to Monday through Friday. I will have to add enough MA to lower pH from 8.2 though.
Money talks!? All it ever says to me is "goodbye!".

Return to “pH & Total Alkalinity”

Who is online at the Pool Help Forum

Users browsing this forum: No registered users and 1 guest