Inconsistency in readings

[ndimtchev]

Hi,

I went to the pool store to get the water tested assuming that they will do a more accurate readings. Shocked to see the inconsistency of the results

Yesterday readings:
CYA 23
TC 2.6
FC 2.6
PH 8.3
TA 82
Adj. TA 75
CH 99
Salt 3200
TDS 4700
Temp 70

Today readings:
CYA 80
TC 3.1
FC 2.7
PH 8.1
TA 81
Adj. TA 57
CH 80
Salt 3200
TDS 5000
Temp 78

- Yesterday I added 4 pounds of baking soda to raise the alkalinity and no other chemicals
- It rained last night

Questions:
1. I cannot understand how CYA can jump from 23 to 80 in one day without adding any more
2. Adjusted TA went down from 75 to 57 -- AFTER adding the baking soda!
3. CH went down from 99 to 80 in one day!

Are these readings possible or the pool store tests are completely inaccurate?
Is it possible that I messed up taking the sample?

Here is a history of the readings this season
5/1 5/2 5/4 5/10 6/2 6/3
CYA 0 0 51 41 23 80
TC 0.8 0.4 0.3 4.7 2.6 3.1
FC 0 0.4 0.3 3.7 2.6 2.7
pH 7.7 7.2 6.8 7.1 8.3 8.1
TA 71 70 44 73 82 81
AdjTA71 70 27 61 75 57
CH 107 98 115 163 99 80


Any recommendations?
(SWG vinyl pool, 35k gals, no heater)

 

[jblizzle]

Welcome to TFP!!!

Any recommendations?

As we tell just about every new member:
1. Read Pool School to learn about the chemistry and methods we teach
2. Order yourself one of the recommended test kits. Pool store testing is worth as much as you pay for it ... as you have discovered.

 

[Bama Rambler]

That's a classic example of why we teach people to do their own testing with a good test kit.

There's a few concerns that you need to know too. To us, the TA was fine, but the PS had you adjust it up which is going to cause you to have to fight the pH. And the pH was already high. That's what you needed to adjust.

As JB said, spend some timereading Pool School and learning how to make your pool sparkle and your pool maintenance Trouble Free!

 

[Richard320]

Welcome!

snip...

Are these readings possible or the pool store tests are completely inaccurate?
Is it possible that I messed up taking the sample?

Here is a history of the readings this season
5/1 5/2 5/4 5/10 6/2 6/3
CYA 0 0 51 41 23 80
TC 0.8 0.4 0.3 4.7 2.6 3.1
FC 0 0.4 0.3 3.7 2.6 2.7
pH 7.7 7.2 6.8 7.1 8.3 8.1
TA 71 70 44 73 82 81
AdjTA71 70 27 61 75 57
CH 107 98 115 163 99 80


Any recommendations?
(SWG vinyl pool, 35k gals, no heater)

It's pretty hard to mess up sticking your arm in a pool with a bottle in your hand. Which leaves us with option two...
Recommendations, you say? :-D

Since you haven't admitted it but have likely been pool-stored, you're no stranger to spending money on your pool. This time, spend it on something that will actually do some good: http://tftestkits.net. I use and recommend the TF100 and a speedstir. I suggest you spring for the XL option now, saves shipping when you need refills later. You WILL use a lot of the FAS-DPD stuff when you first start. It's normal; we all obsessed over it when we got our new toy.