Pool water slightly darker than usual?

[smithj51]

Fiberglass pool, 8k gallons
2.2 FC
7.7 pH (too high)
87 CYA
118 TA
165 calcium hardness (low)

It’s not any specific color but it is a bit darker than usual, especially at the deep end vs. the shallow steps. My best guess is metal accumulation from all the recent rain. Is that a reasonable guess? Should I add a sequestering agent? If so, the instructions say to stop chlorinating and wait until it drops to 0, then drop the ph to 6.8 before adding the sequestering agent. Do I really need to do all that? Seems risky to drop the chlorine to 0.

Thanks!

 

[ajw22]

I would not assume based on the way water looks and no test data.

Those look like pool store tests and not a test from your own test kit.

If we were to believe the test data your FC is too low for your CYA.

Can your pool pass a Overnight Chlorine Loss Test? If not, you have algae and need to follow the SLAM Process

 

[smithj51]

I would not assume based on the way water looks and no test data.

Those look like pool store tests and not a test from your own test kit.

If we were to believe the test data your FC is too low for your CYA.

Can your pool pass a Overnight Chlorine Loss Test? If not, you have algae and need to follow the SLAM Process

Thanks for the speedy reply! They are test results from the WaterGuru Sense S2 which measures once daily.
Unfortunately I don’t think I can do an overnight chlorine test because I have an in-line chlorinator, and even when I turned it off / closed the valve in the past, the chlorine levels kept rising (this was actually my first post on TFP). Is there a way to test for metal, and/or another way to test for algae? I have a Taylor test ki, and test strips that can test for bromine but not copper or iron which I think are most likely if metal is the problem.
I did have a few days of FC less than 1 ppm recently which supports the algae theory.

 

[proavia]

What exact Taylor test kit do you have?
How old are the reagents?
Test Kits Compared

 

[smithj51]

What exact Taylor test kit do you have?
How old are the reagents?
Test Kits Compared

Taylor K2005
Delivered March of this year

 

[ajw22]

Unfortunately I don’t think I can do an overnight chlorine test because I have an in-line chlorinator, and even when I turned it off / closed the valve in the past, the chlorine levels kept rising (this was actually my first post on TFP).

Show us pictures of your equipment pad and chlorinator plumbing.

Is there a way to test for metal,

Pool stores can test for iron and copper.

and/or another way to test for algae?

Not really.

I have a Taylor test ki, and test strips that can test for bromine but not copper or iron which I think are most likely if metal is the problem.

Metals cause staining or change the water color from blue to green. What you describe does not sound like metals.

 

[ajw22]

Taylor K2005
Delivered March of this year

The Taylor K-2005 is a test kit that gets pushed by many larger “pool stores”. It tests pH, TA, CH, CYA VERY well, but it’s shortfall is how it tests chlorine levels. The K-2005 uses a “DPD” chlorine test which has three very large pitfalls:

1. The DPD chlorine test will NOT show accurate results above 5 ppm. This is an issue if you wish to follow TFP methods, as we teach that it’s best to maintain a ratio of chlorine to CYA, see the Chlorine/CYA Chart, not just a firm 1-4 ppm.

2. The DPD chlorine test uses “color-matching.” You add a few drops of reagent to the water and then match the pink sample color to the comparator. It’s easy to mismatch the true levels.

3. Perhaps worst of all, the DPD chlorine test's pink sample color can "bleach out." If the chlorine is well above the 5 ppm limit, the pink sample color after the reagent is added can fade out or even remain clear. This can lead one to believe the chlorine level is MUCH lower than reality, potentially leading to adding even more chlorine to the pool.

In short, the K-2005 is a good kit.........it’s just not very accurate in chlorine testing.

TFP Methods requiring FC of more than 5 ppm, such as the SLAM Process and higher CYA levels, cannot be tested with the DPD chlorine test in the K-2005. You need the FAS/DPD chlorine test found in the TFT Test Kits, Taylor K-2006 or K-2006C.

If you have the K-2005 you can separately buy the FAS/DPD Chlorine Test to make your kit equivalent to the K-2006.

 

[ajw22]

87 CYA

Post a compete set of tests from your K-2005.

For CYA > 90ppm, repeat the test adjusting the procedure as follows:

1. Fill the mixing bottle to the lower mark (15 ml line) with pool water.
2. Continue filling the mixing bottle to the upper mark (30 ml line) with tap water.
3. Shake briefly to mix.
4. Pour off half of the contents of the mixing bottle, so it is again filled to the lower mark (15 ml line).
5. Continue the test normally from adding R-0013, but multiply the final result by two.

If you need to dilute the pool water further then apply these ratios:

Pool water	Tap or distilled water	Multiply result by
1	1	2
1	2	3
1	4	5

Note that when doing a diluted test not only do you multiply the range of the test you multiply the error rate of the test, so results are a ballpark - not an absolute.

See CYA Testing for tips in how to read the test results.