TA readings using TF100 "totally disagrees" from Pool supply store

[Njflynnx]

Ok.. I’ve been doing this for I bit, but I’m totally confused with how my readings and results can be sooo different from our local pool supply house. I pulled a sample and did my tests.. TA came to 70... I added 2+ lbs of soda.... I then took the remaining sample water to TexSun and they tested with their BioGuard system and came up with a reading of 38?.? No way! They wanted me to add 15 lbs of soda... that was 3 hous ago.. so I tested my water again.. and my results are as predicted since I added the soda.. @ 90...

how can they get it sooo wrong...???

 

[Texas Splash]

To add to your confusion and frustration, try taking the same water sample to 2-3 stores. Wait until you see those numbers. It just never ends. Welcome to the forum!

 

[Donldson]

Pool store numbers so unbelievably wrong you just can't wrap your head around it?

Welcome to TFP

 

[Rancho Cost-a-Lotta]

I’m totally confused with how my readings and results can be sooo different ...They wanted me to add 15 lbs of soda

I think you probably figured it out on your own. Spend some time around here and you will see how common your experience is.

 

[JamesW]

38 is probably the "Adjusted" TA, which is the TA minus the CYA correction factor, which is usually about CYA/3.

So, if the TA is 70 and the CYA is 100, the adjusted TA is 70-(100/3) = 38.

 

[Njflynnx]

Re: TA readings using TF100 "totally disagrees" from Pool supply store

I’m confidant my readings and the pool appearance agree.. but... what about those poor suckers going in, not knowing any better and walking out with 15lbs of soda to screw up thier pools.... does it do any good to call them on it? I just said thanks and went Home....

feeling bad bad for my fellow man....

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So if that’s the case... yes CYA is ~100.. do I really need to add 15 lbs of soda?

 

[JamesW]

Mostly, go by the pH. If the pH is rising, lower the TA. If the pH is falling, raise the TA. If the pH is stable, leave the TA where it is.

You should start working the CYA down some.

Also, run your numbers in PoolMath to check your CSI.

 

[cubbybeave08]

Re: TA readings using TF100 "totally disagrees" from Pool supply store

I’m confidant my readings and the pool appearance agree.. but... what about those poor suckers going in, not knowing any better and walking out with 15lbs of soda to screw up thier pools.... does it do any good to call them on it? I just said thanks and went Home....

feeling bad bad for my fellow man....

- - - Updated - - -

So if that’s the case... yes CYA is ~100.. do I really need to add 15 lbs of soda?

I always advise those who use TF 100's for those pools...I have two neighbors who do... to always go by your test kits and trust yourself and your results...I took my water to the pool store one spring after I opened and balanced just to see what they would tell me. Oh man if I would have followed their advice. Remember their job is to sell you stuff. They can't sell you stuff if you don't need it.

I buy a 4 lb box of Borax and a two pound box of Arm and Hammer in the spring...along with some CYA, and my liquid chlorine...and that is all. I buy two cases every two weeks and never spend more than $150 or $200 over the course of the summer. I am a long time member here, but very seldom post or ask questions because the people here have taught me so well. Trust your kit. It's why they tell you to get it. So you don't have to trust anyone else.

 

[borjis]