Help me understand Chlorine!

[newbieForNow]

Hello everyone,

New house/pool owner here since August and I'm having a hard time understanding the different chlorine results I'm getting which causes me to doubt my ability to take care of the pool myself.

My issue is that I don't know who and what to trust or at least how to understand the results I'm getting. See my pool equipment in the footer.

I always seem to get higher chlorine level results with my Taylor kit than with any other method. The difference is usually high.

For example, on my last test (FAS-DPD), I measured 27ppm of FC with the Taylor kit using 10ml and multiplied by 0.5 as per instructions. The instructions also say to record that number as FC. When doing the CC test, no CC is present.

If I use a test strip, I get a very high (>10) TC , but only 5 ppm of FC. Whatever method my pool guy used, also reported 5 ppm of FC. A water sample in a store also showed 5 ppm TC, 5 ppm FC, and 0 ppm CC.

At first, I thought it was me taking too long, so I bought a Taylor magnetic stirrer but I got the same results. The reagents are not expired and are not stored in the sun. Could it be me doing something wrong? The reagent is bad? Am I correct and everything else is coincidentally getting the same result?

The very high TC in the strips seems to match what my FC test is on the Taylor test but then that would mean I'm measuring TC which is not what the kit says you're measuring. I don't know, I'm just confused. Please help me understand the science behind this lol

Other things that show high chlorine is the alkalinity test is not green to red is blue to yellow. PH once turned purple but two subsequent tests showed 7.2~7.4.

Full test:

My test with Taylor kit:

FC 27 ppm
CC 0 ppm
PH 7.4
ALK 80 ppm
CH 230 ppm
CYA 55 ppm
SALT 3200 ppm - matches the qty in the Chlorinator screen.

Store Test:

TC 5 ppm
FC 5 ppm
CC 0 ppm
PH 7.4
ALK 80 ppm
CH 250 ppm
CYA 60 ppm
SALT 2800 ppm

* Very similar results except for chlorine.

 

[PoolStored]

Other things that show high chlorine is the alkalinity test is not green to red is blue to yellow.

This is your clue...when FC is high, TA test is blue to yellow.

What is the date on the reagents/when did you buy them? Buying reagents from Amazon, sometimes they can sit in a warehouse and not last as long. That is why I buy from TFtestkits.net guaranteed fresh. It may be reagents.

The only other issue may be your testing technique. Clean the vial with rubbing alcohol and dry. Then, test again. Wipe the tip of the reagent bottle with a wet paper towel (will remove any static). Then hold the reagent vertical and SLOWLY squeeze...allow the drops to form and drop under their own weight. If you squeeze too fast, the drops are too small and you get a higher result.

Water Testing Errors - Further Reading

www.troublefreepool.com

 

[dereksanders]

What is the expiration dates of your powder and reagent? All your other tests have reasonable values so it appears you are testing correctly.

 

[newbieForNow]

Exp Date on both the reagent and powder is 05/25. I did buy the kit from Amazon.

I haven't cleaned the vial with rubbing alcohol or wiped the tip with a paper towel. I did read on another thread that the bottle tip could have a manufacturing issue causing the drops to be of the wrong size. Not sure if that could be possible

What is the expiration dates of your powder and reagent? All your other tests have reasonable values so it appears you are testing correctly.

This is your clue...when FC is high, TA test is blue to yellow.

What is the date on the reagents/when did you buy them? Buying reagents from Amazon, sometimes they can sit in a warehouse and not last as long. That is why I buy from TFtestkits.net guaranteed fresh. It may be reagents.

The only other issue may be your testing technique. Clean the vial with rubbing alcohol and dry. Then, test again. Wipe the tip of the reagent bottle with a wet paper towel (will remove any static). Then hold the reagent vertical and SLOWLY squeeze...allow the drops to form and drop under their own weight. If you squeeze too fast, the drops are too small and you get a higher result.

Water Testing Errors - Further Reading

www.troublefreepool.com

 

[PoolStored]

I did read on another thread that the bottle tip could have a manufacturing issue causing the drops to be of the wrong size. Not sure if that could be possible

This is exceedingly rare...I think I've only seen it once in thousands of threads.

Water testing errors is exceedingly common.

Sometimes reagents have not been store properly before shipment and they go bad before the expiration date. I have had this happen with salt test reagents and the FAS-DPD reagent.

I would lean toward your FC is high (TA test yellow)...you may have confounding issues that lead to an FC test being higher than actual...bad reagents, testing errors, or your FC is in fact 27.

Re-try the test. Cleaning removes any residue that would interfere with the test. The wet paper towel will remove any static charge if it exists (only need to wipe once before you start.

I measured 27ppm of FC with the Taylor kit using 10ml and multiplied by 0.5 as per instructions.

So we understand, it took 54 drops to clear the sample, you multiplied 54 x .5 to get 27 FC?

 

[aussieta]

also if you take too long doing the test the sample will turn pink again
one drop per second and as soon as it goes clear that is it,
if you wait a few seconds it will go pink again

 

[newbieForNow]

This is exceedingly rare...I think I've only seen it once in thousands of threads.

Water testing errors is exceedingly common.

Sometimes reagents have not been store properly before shipment and they go bad before the expiration date. I have had this happen with salt test reagents and the FAS-DPD reagent.

I would lean toward your FC is high (TA test yellow)...you may have confounding issues that lead to an FC test being higher than actual...bad reagents, testing errors, or your FC is in fact 27.

Re-try the test. Cleaning removes any residue that would interfere with the test. The wet paper towel will remove any static charge if it exists (only need to wipe once before you start.


So we understand, it took 54 drops to clear the sample, you multiplied 54 x .5 to get 27 FC?

Just retested with all your tips.

- Cleaned the vial
- 10mL water sample on Taylor magnetic stirrer (measure before dropping in the stirrer)
- Used 1 scoop of R-0870
- Wiped the tip of R-0871 with a dry paper towel
- It took 55 drops of R-0871 to turn clear
- 55 x .5 = 27.5 ppm FC

I do think I have high FC because the Alkalinity test is turning blue, and that one time when the PH test turned purple. I might get new reagents to make sure these didn't go bad and the FC are actually these high but even with the unreliable strips (which show 5 ppm of FC) they are detecting over 10 ppm of TC. I don't trust them, but there's something they are detecting that's giving those results.

Let me know what do you think.

 

[PoolStored]

It is probably not worth doing again...but use a wet paper towel. The static is typically on new bottles from shipping. Not likely an issue in your case...I wouldn't test again.

So, two things you can do...
1) Until it comes back down, use 5mL sample and 1 drop = 1 FC. This will save you reagent. Revert to 10mL sample when FC comes down.
2) order new reagent and see if it is any different...DO wipe the tip on the first test with a WET paper towel. We have seen lots of static when they arrive... R-0871 FAS/DPD Reagent

 

[newbieForNow]

It is probably not worth doing again...but use a wet paper towel. The static is typically on new bottles from shipping. Not likely an issue in your case...I wouldn't test again.

So, two things you can do...
1) Until it comes back down, use 5mL sample and 1 drop = 1 FC. This will save you reagent. Revert to 10mL sample when FC comes down.
2) order new reagent and see if it is any different...DO wipe the tip on the first test with a WET paper towel. We have seen lots of static when they arrive... R-0871 FAS/DPD Reagent

Will do. Thanks!

 

[PoolStored]

Ok, so let's address WHY your chlorine is so high.

As we go through the season, you get more uv in the summer months, less in spring/fall, and even less in the winter.

You need to adjust your cell output, and/or your pump runtime to adjust FC that gets added.

With a CYA of 60, you might use 3-5ppm FC in the summer, maybe 2-3 in spring/fall and 1-2 in the winter (these are just example numbers).

You cell in your pool, will generate 8ppm FC running 50% for 12 hours. You have a good sized cell for your pool.

But if you don't adjust the output for the season, you can add significant FC.

Did you make any adjustments to the cell output% or run time as you went through Aug/Sep/Oct? If not, that is your source.

 

[AUSpool]

Geday newbieForNow and welcome to TFP.

Trying to compare test results between different kits or store and home tests never goes well. I was in that same position when I first started.

I guess the swim season is coming to an end in Florida, the temperatures drop the UV declines. With a SWG it’s easy to overdrive the output and end up with high FC as the swim season ends.

The store testing is most likely with a Lamotte spin disk and if that is the case all of there results are void when the FC is over 10ppm.

I would turn you cell off for a few days and watch your FC come down.

The Taylor pH test is compromised when the FC is over 10ppm. It will show as purple while you saw. I’m not sure why you’re seeing 7.2 -7.4 again. I assume you managing the pH with acid or have a pH controller. If your FC doesn’t start to come down I would think about new FAS/DPD regents from TFtestkits but I’m not sure if the sell them individually.

I’m not sure who sells what or how long stuff is warehoused for before shipping but my K200C was bought through a local store and drop shipped direct from Taylor.