Chlorine Testing

[pgjohnson]

Hi,

PH 7.6
FC 3.94
TA 60
CYA - 39
SALT - 3200
CH - 413

Have been reading as much as I can on here and it has always been helpful. Decided to get a better method for testing chlorine more accurately and so bought the FAS-DPD kit from clear choice labs (Australia).

I have tested 3 different times, on different days (within 3 days) and times of the day and have got the same result, 12 drops added so FC of 6ppm. The discrepancy comes when testing against other methods:

Test using DPD tablet: Between 2 and 5 ppm but closer to 2ppm
Test using test strips: Between 3 and 5ppm
Pool shop 1: 3.94ppm
Pool shop 2: 3ppm (day after pool shop 1)

Now I know all the above methods are meant to be less reliable but the fact they are all close to each other (even the 2 independent pool shops) but this makes me very much doubt the more expensive and recommended kit from clear choice labs.

Any advice/help would be greatly appreciated. (Have sent email to clear choice labs also to enquire)

 

[proavia]

If you use less reliable methods, you will get less reliable results.
Even if those other results are close to one another, they are less reliable.

Have a read thru the extended test kit directions. You may need to adapt them a bit for the Clear Choice test kit, but they may help you with testing.

Extended Test Kit Directions Archives

www.troublefreepool.com

Are you using an electronic stirrer?

Post your results from your Clear Choice test kit
FC
CC
pH
TA
CH
CYA
Salt
Water temperature

Are you using PoolMath?

 

[pgjohnson]

If you use less reliable methods, you will get less reliable results.
Even if those other results are close to one another, they are less reliable.

Have a read thru the extended test kit directions. You may need to adapt them a bit for the Clear Choice test kit, but they may help you with testing.

Extended Test Kit Directions Archives

www.troublefreepool.com

Are you using an electronic stirrer?

Post your results from your Clear Choice test kit
FC
CC
pH
TA
CH
CYA
Salt
Water temperature

Are you using PoolMath?

I only have the clear choice labs chlorine test, but still 4 different methods (even if less reliable) to 1 does seem like a discrepancy. Read the link and following instructions correctly.

 

[proavia]

How do your other test parameters compare?

Post a complete set of test results from the CC testkit.
FC
CC
pH
TA
CH
CYA
Salt
Water temperature

Hopefully you'll hear from Clear Choice soon.
Let us know what they have to say.

 

[Dirk]

How do your other test parameters compare?

I only have the clear choice labs chlorine test

Gene, if I'm reading this thread correctly, he didn't buy the kit, only one of its tests, the chlorine test... So he can't post the other results.

@pgjohnson, do the components of the chlorine test have any expiration dates on them?

 

[mgtfp]

The CCL titrating reagent is usually quite good. But I sometimes had issues with the droppers. They are more sensitive to the applied pressure and more prone to air bubbles than Taylor droppers. They have been introducing new, better, droppers, not sure if all reagents have them yet.

Try to apply as little pressure as possible, keep the bottle vertical. If you get air bubbles at the beginning, then release them first, and then make sure to not let air back into the bottle while counting drops.

I have a lot more confidence in the CCL test compared to the other options you listed.

 

[Mdragger88]

@pgjohnson
Please understand that part of the reason for the recommendation of the fas/dpd test is not because it is sooo much more accurate at low fc levels but rather at the higher fc levels we recommend people maintain
See—>> FC/CYA Levels


& that can be required when clearing up a problem (doing SLAM Process)
As mentioned- all of the tests are this way. So the whole kit should be used for all the parameters- not just fc & cc.
Accurately measuring fc is only one piece of the puzzle- the recipe may not turn out the same if you’re using a bad cya measurement from a strip or a pool store.
You need to ensure that all the measurements are accurate & repeatable.

 

[pgjohnson]

Thanks everyone.

First off got an excellent response from Clear Choice Labs, who are very much willing to help, so great customer service. Possibly sending me new dropper. And I agree, they are probably going to be the most reliable.

Can't see any expiration dates.

Tried to do another test this morning, was being as accurate as I can and got 9 drops, 4.5ppm. Did do a DPD tablet test after and looks around 2ppm colour gradient, going to check with shop also.

Ok so maybe not as accurate at low levels but are you saying that chlorine could be 3ppm but reading around 6ppm for any test? Seems like quite a difference and I was more trying to understand how 3 or 4 less reliable methods are in the same range but fas/dpd way different?

Anyway happy to be told I'm not doing something right, ultimately just want to be confident I'm at least maintaining the minimum chlorine required. I am happy with my other results as they have been stable over many months and pool is looking great.

Any advice is most welcome. Thanks

 

[Dirk]

You're missing an overarching principle that negates most of your concerns. (And this is a little anti-establishment, so bear with.)

It's really not about the actual number, and how accurate it is. It's about testing in a consistent, repeatable way. Even if you could get a super accurate FC number, you can't apply that number in your pool like others do in theirs. Every pool is different. Every set of variables is different (number of swimmers, fill source chemistry, attacks from kids and animals and foliage, how well your filter and skimmer work, ad infinitum). How FC4 works in your pool might give someone else's a green tinge. And vice versa. The TFP charts and numbers we provide are for guidance, they are "mostly true," and work for a lot of people. But they are not in stone. You must verify and/or develop your own set of minimums and targets and ranges, using TFP guidelines as a reliable starting point.

Here's an example.

I test using Taylor's FAS-DPD kit, and I trusted TFP numbers to establish my target FC, and so my chlorine dosing. And I have developed a very strict MO for testing, which I follow religiously and consistently.

I let my pool get away from me one summer and my FC dropped. (Hot week, pool party, and me a little lazy.) I got a tinge of green. I tested the FC and it was slightly higher than the TFP minimum. At that point I was able to confirm where my pool's minimum FC level actually is, even though slightly higher than TFPs.

It didn't, doesn't, matter what the actual minimum number is. It didn't, doesn't, matter what my test result number was. I now know that with my particular MO for reliable testing, if I test and get X, and Y is where I go green, if X is too close to Y, then I gotta add chlorine. And more importantly, I gotta keep my FC at X + 4 so I never get near Y again. See what I mean? It doesn't matter that X or Y are what TFP dictates, it only matters that X and Y are what my pool dictates! And it really doesn't even matter if your FC testing is 2 or 3 off. Because if and when your pool gets a little hazy (your established minimum), the FC you test at that point will be the same 2 or 3 off. Get it? What's important is that your pool's minimum and your test results are relative to each other. Not how they relate to TFP's chart, or a pool store's results, or some other testing kit's results.

Where one would get into trouble is by using inconsistent testing methods, or mixing/matching test results from entirely different testing systems. Forget what your other sources are telling you. Test your water with one reliable kit, and don't use or even look at any others. If you make it through a season with your FC result and subsequent dosing, no matter what the actual numbers are, then you know how to test and dose accordingly, for your particular pool and its particular variables. That's all that matters. If you keep getting hazy water or green patches, then your FC is too low. It doesn't matter if it's inside or outside of TFP's guidelines. Your pool tells you what it wants, not the pool store, not TFP.

Stop worrying about the numbers, and definitely ignore competing numbers. Focus on establishing really good testing procedures, using only one quality test kit, and stick with that MO.

If you'd care to hear about what I think "really good testing procedures" means, I'll be happy to share an equally long post!

 

[pgjohnson]

First off pool shop just came back at 3.8 this morning compared to the 4.5 so much closer.

But forget all that, Dirk thanks so much get exactly what you mean, perfect explanation. Issue was really using the DPD tablets which give a very poor range for reading, hopefully CCL better now.

What was worrying me so much was making sure it was at least 2 if my CYA is around 40. So I would be testing on a daily basis (DPD tablet, so hard to read gradient) to make sure pool did not drop and did not go green. Getting the CCL kits was hoping to limit my testing to only like once a week if I knew it was like 4ppm at the beginning of week and nowhere near 2ppm. So guess I will just say like the 4.5ppm is my baseline and check in a few days, how often should I be testing? Have some crazy hot weather then lots of rain so difficult to get SWG set right.

If it did drop below a baseline when it starts to go green can you get it back on track with just chlorine increase?

Side question: Phosphates at 0.787 and from my reading on this forum that seems fine. Obviously pool shop says its bad (want at 0.2 or below) and tries to sell me stuff. Question is, do phosphates ever go down without phosphate remover, does chlorine kill phosphates or will I get annoyed by the pool shop each time I go

Really do appreciate all the help.

 

[mknauss]

will I get annoyed by the pool shop each time I go

Easy fix. Don't go to a pool shop.

Ignore phosphates. There are few, very few, times to be deal with them.

 

[Dirk]

You really have to stop talking to anyone at the pool shop. They have a massive conflict of interest. They want to sell you the things that they claim will counteract the readings they are providing. It is their business model to convince you to buy thing based on their test results. Does that sound in your best interest? Just stop.

You are still stressing FC too much. This is what I and some others here do. Use the low point of the TFP target range as your minimum. Use the upper values or the target range as your target. At CYA70, my minimum is 3 and my target range is 5-10. I threw "3" out. I use 5 as my minimum. That is my red-alert-stop-everything-add-chlorine alarm. I treat 4 like the end of the world. That way, I never get anywhere near 3. I target 7 to 8 for normal FC. I build in this extra buffer just so I don't have to stress like you're doing. I will virtually never get algae this way (never have), and I don't have to even think about it. Ever. And if a gopher dies in my skimmer and start consuming my FC, I have enough buffer to keep from getting algae (which is why I check my skimmer everyday in the hot part of summer).

If you're trying to ride 2, you're going to get stung. Green. Get it up to four or five and play it safe. There is no harm to you or the pool with slightly elevated FC. You might use a little extra (excess FC will burn off more quickly than that amount "protected" by CYA), but what is your stress level worth to you? A few extra bucks a week? You're playing with fire. Relax. Overshoot chlorine a little until you better understand what your pool wants. It's OK to go a little high, it can be a nightmare when it goes too low.

I solved my one slip, a tinge of green on my east wall, with added chlorine. I think that was more me getting away with it, than a hard and fast MO. It might work, it might need a full on SLAM. I just lucked out. There's no way I can predict. Again, your pool will tell you what it needs. Bump the chlorine, see what happens. If it clears up and you can pass an OCLT, then you're golden. If not, your pool is telling you to SLAM.

I pay zero attention to phosphates. Never have. My understanding is that too much phosphates can "feed" a green pool. If you never have a green pool, phosphate level doesn't matter. If you keep your FC well above the bottom of your target range (forget the minimum number, see above), then you'll never have algae and phosphates won't matter and it's one less thing to worry about. Again, why is the pool store so concerned about your phosphate level? Come on, you know the answer!!

I have an SWG, so I only test once a week, to make sure it's working. If you're adding chlorine manually, you'll need to test more often. Same worn out record again, listen to your pool, it'll tell you how often to test. If you test every day, and find that you need to restore FC every day, then your pool is telling you to test every day. (It's also telling you to buy an SWG!) If you test every day but consistently only have to add chlorine every third day, then your pool is telling you it's OK to take a day or two off between testing. Just listen to it.

And you can even guess a little about what you know it's going to tell you. If you're in for a few days of coolish weather and clouds and rain, you can skip a test. If you're in blazing hot weather, then test more often. Pool maintenance is as much art as science. But you use the science to refine the art.

 

[Dirk]

Easy fix. Don't go to a pool shop.

Ignore phosphates. There are few, very few, times to be deal with them.

Oh sure, anybody can write two sentences. But I can say the same thing in only six paragraphs!!

 

[pgjohnson]

Yeah thanks everyone. Do have the SWG, just difficult to adjust with the weird weather.

Will set my new level at like 4/5. was not really trying to keep at 2, just could not really tell anything above 2 confidently without visiting pool shop. Was just not sure on the reliability of the new CCL telling me its 6 when its only possibly 3. And then moving from 6 to 4.5 in a few days with pool shop not really moving, but that could have been me with testing accuracy. Will see how I go tomorrow.
But now will use the CCL test benchmark currently (4.5) and keep the chlorine level above that.

Thanks again been really helpful.

 

[mgtfp]

Side question: Phosphates at 0.787 and from my reading on this forum that seems fine. Obviously pool shop says its bad (want at 0.2 or below) and tries to sell me stuff. Question is, do phosphates ever go down without phosphate remover, does chlorine kill phosphates or will I get annoyed by the pool shop each time I go

Phosphates are algae food. As long as there is no algae around to feast on phosphates then their presence doesn't change a thing. And that's what chlorine is for - as long as you follow the recommended FC/CYA Levels, algae shouldn't have a chance.

Removing phosphates can buy some time before a pool turns green, should the chlorine supply fail. I see it as optional, doesn't hurt, but complicates pool maintenance a bit. Easier and more foolproof is to just maintain sufficient FC levels.

Some equipment manufacturers (mainly for SWGs) won't accept warranty claims when there are phosphates in the water. That's probably the main indication where phosphate removal is advised - prior to lodging a warranty claim.

Extreme phosphate levels in combination with extreme CH can lead to calcium phosphate scaling, but that really is more of an oddity.

 

[Mdragger88]

Don’t try to play kissy face with minimum. Its a sure fire way to get bit by an equipment failure, high uv day, higher bather load, or other environmental conditions.
I like to aim for 10% of my cya or even a scootch higher so there’s always a buffer. Much easier & less stressful!
Btw- a cya of 40 is a bit low for a swcg pool. That will have your swcg working hard to keep up.
Once you’ve got your full kit & have a reliable cya number & have passed an
Overnight Chlorine Loss Test
you can then adjust it to the 60-80 range. The more uv you have the more protection from the sun your fc needs as it’s being made slowly over time by your swcg. So around 60 in the shoulder seasons & possibly up to 80 in the peak of summer.
What I meant about the 3ppm thing was that other test methods (strips & the store tests) get bleached out or skewed/have limitations at higher fc levels(above 5ppm) so even if they are relatively close at low ppms it gets increasingly less reliable as fc increases. The entire test strip will be skewed for instance - not just the fc part. You got the right stuff fas/dpd so stick with that. Don’t worry with the pool store unless you need something from the list & wish to patronize their establishment.

Recommended Pool Chemicals

Which should I buy? TFP's recommended pool chemicals are cheap, easy, and won't unbalance your pool water.

www.google.com

 

[Dirk]

And then moving from 6 to 4.5 in a few days with pool shop not really moving, but that could have been me with testing accuracy.

See? You could be looking at that all wrong (and probably are). You keep assuming the pool store's results are accurate, and that yours are faulty, when the opposite is actually far more likely. It's more likely the pool really did go from 6 to 4.5, and the pool store got it wrong both times, or just one time, but their inaccuracy just coincidentally produced the same result, with one or both of those results being wrong! You've just been assuming its you.

They don't hire experienced chemists. They hire pimply-faced teenagers, and sometimes just summer help, ram them through a quickie course of how to test, and then let 'em loose on the public. Management doesn't care about the accuracy of the results, as long as the actual result is that the test results result in sales! OK, while I'll admit that could be an exaggeration in some stores, I know for a fact that many stores work just like that.

Point being: trust your test results. Odds are you are going to be using better methods that get better results, especially after a little experience. And to beat this horse up a little more: even if your methods are producing a slightly skewed result, it won't matter. As long as you reproduce your test procedures faithfully, doing them the exact same way each time, your results, even if skewed, are more useful, because they'll be skewed by the same amount each time. You're looking for the difference in FC from test A to test B.
4-3=1.
5-4=1.
It's the "1" you're after, not so much the 3 or the 4 or the 5.
"I dosed 4 cups of chlorine today because I had an FC that was 1 less than yesterday." We don't teach it that way, but that's what's actually going on. Testing FC is about determining how much chlorine to pour in each time, not really about what the test result numbers were.

The problem with pool store results is that there are a handful of people, each doing it slightly differently from each other each time. That's why pool store test results are so spotty, and why we don't trust them. It's not the equipment so much as its the constantly revolving staff. When you do your own testing and trust it, there is no revolving staff. It's all you.

If I'm confusing you, that's OK. Just ignore me. Like I said, these long-winded explanations are a little anti-establishment. I'm just sharing the way I wrap my brain around testing and results and dosing. I wouldn't expect others to think the same way. Just a different perspective is all. And perhaps only a perspective about my addled brain!

 

[pgjohnson]

Agree. Don't trust the pool shop although this shop uses a spinning machine so can't really be user error but I guess could be out some other way.

But I get the point, will now use my tests with the new CCL kit as the baseline and make sure I stay above that. I think a test tomorrow, as accurate as I can and see the result will be helpful.

 

[Dirk]

although this shop uses a spinning machine so can't really be user error

Well, that's certainly the illusion they're meant to convey. Those machines need to be setup, maintained, calibrated regularly, cleaned each use, etc. Then used properly. There are plenty of ways human error gets introduced. The results are merely faster, not necessarily better.

 

[pgjohnson]

I definitely get your point and thanks so much to all of you for all the help.