When to react to changes in the test results.

pb4uswim

Well-known member
Jul 23, 2020
313
Michigan
Excluding CL and PH, I thought the rest of the numbers usually stayed pretty stable. Below are two test results about a month apart. Question is basically whether or not I should react to the most recent numbers. Or, should I wait a week and retest and see where things are heading. My concern is that the CH went down a lot. I know with a fiberglass pool, that may not be a big concern, but it makes me wonder - did I do the test wrong (twice), are my regents going bad, was there something different about the water (temp, circulation . . .) or, is it time to add more calcium? Also wondering about the salt.

Note, the April test is just after opening. Since then, we’ve only swam a few times as the temp is not yet warm here. I’m not concerned about the numbers in general, but wonder when to think about tweaking any of the numbers. Thanks.

Results from 4/9/21
FC 3.5
PH 7.2
TA 70
CH 250
CYA 70
Salt 3200

Results from 5/16/21
FC 6
PH 7.3
TA 70
CH 150
CYA 60
Salt 2800
 

zea3

Mod Squad
TFP Expert
LifeTime Supporter
Jul 10, 2009
13,990
Houston, Texas
Do you have an autofil on the pool? Have you had a lot of rain? How old are the reagents, and where do you store them? Do you use a speed stir for your tests? CYA, CH, and Salt all went down, and those are values that usually only go down with water replacement. I would try and determine first if a leak or rain is responsible for a some water replacement.
 

pb4uswim

Well-known member
Jul 23, 2020
313
Michigan
The pool is new last year so the regents are just coming up on one year. They are stored in my house. There hasn’t been a lot of rain. We opened it and they cleaned out the pool and vacuumed to waste (brought their own pump and just dumped the water in my yard) and since then, the pool has remained at about the same level.

Note that the tests are both from this year and only a month apart. My last full test of last year was in September 2020 as follows:

FC 7.5
PH 7.7
TA 85
CH 200
CYA 70
Salt 3200
 

IceShadow

Gold Supporter
TFP Guide
Jun 8, 2019
2,612
Milwaukee, WI
Pool Size
20000
Surface
Vinyl
Chlorine
Liquid Chlorine
CYA, CH, and Salt have all dropped. It would correspond to water being removed through backwashing or a leak and adding new water without those things. If you haven’t added water, then the only thing I can think of is testing error.
 

pb4uswim

Well-known member
Jul 23, 2020
313
Michigan
CYA, CH, and Salt have all dropped. It would correspond to water being removed through backwashing or a leak and adding new water without those things. If you haven’t added water, then the only thing I can think of is testing error.
I'm guessing some sort of testing issue. I'll run the pump overnight and test in the morning. I've been running the pump for 5 hours every morning to get chlorine, but I did test after the pump was off for a couple hours. Maybe that's all that's going on. Of course I'll double check my testing work because there's always the possibility I just messed up.

Thanks.
 

Bperry

Gold Supporter
Aug 20, 2020
782
Knoxville, TN
Pool Size
27000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
CircuPool RJ-60
I'm guessing some sort of testing issue. I'll run the pump overnight and test in the morning. I've been running the pump for 5 hours every morning to get chlorine, but I did test after the pump was off for a couple hours. Maybe that's all that's going on. Of course I'll double check my testing work because there's always the possibility I just messed up.

Thanks.
Are you testing every day or just once a month?
 

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pb4uswim

Well-known member
Jul 23, 2020
313
Michigan
So, my guess is that the first set of numbers were off - the first tests upon opening the pool. I've redone the tests a couple times, making sure that the pump had run several hours, and I'm coming out about the same. I'll post my most recent set of tests in a new thread to ask some follow up questions. Thanks for the help.

Results from today
FC 6.5
PH 7.5
TA 70
CH 150
CYA 60
Salt 3000

It's worth noting that the salt being different by 200 or 400 is really only the difference between one or two drops of the reagent. Easy enough for me to be off by one or two drops. I'm now comfortable that 3000 is an accurate test result. Not sure what happened to the CH and of course we all love the CYA test. :)
 
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