Life expectancy of pool test kit

[ciaka]

I store all mu chemicals in house air conditioned dark space. Wonder how that changes life expectancy of the chemicals in the kit.
How long should I expect to continue using chemicals in the kit.
Is there a ballpark in years or months? Or is it one of those 'replace' by expiry dare?
Looking for some guidance from those who have experience vs hearsay.

I've been told by chemists not specific to pools but in chemistry industry, that chemicals very often last way past expiry date if stored in air conditioned dry dark places. Thats whybi wonder. Thank you.

 

[ajw22]

How will you know when your chemicals are going bad?

I find replacing reagents every 2 years with the TFT March discount is a good compromise. By then some of the reagents are running low.

 

[ciaka]

That's the thing you likely wouldn't know unless you had old and new chemicals, and did 2 tests at same time to compare. Folks in chemistry industry spoke in general terms, so I don't know how applicable that is. And trying to see if anyone on here investigated this or has researched answers.

 

[DrewLG]

The manufacturer says the reagents should be replaced every year. But you can test them yourself to see when they go bad:

Buy a full refill when your kit is a year old, but keep the original reagents. Every few months, perform a full test with the old reagents and compare the results to what you're getting with the new reagents.

 

[Donldson]

That's the thing you likely wouldn't know unless you had old and new chemicals, and did 2 tests at same time to compare.

Well, if you add X amount of a chemical to your water and the testing shows the expected change, then that's a pretty strong indicator.

Taylor sells standard solutions which are the best way to verify ones chemicals and procedure are giving accurate answers. After all, just because two separate testing methods give the same results doesn't mean they are both giving accurate results.

 

[Newdude]

The refills for the 3 kits go on sale each March in the low $40s.

Usually at least half of my kit is getting low and won't make it the full season. I use up the existing FC/ CYA / CC drops and throw out the rest which would have lasted me forever.

If I bought the giant bottles from amazon, I'd go 2 years for everything but the FC powder. It's humid here so even with the dessicant pack, and more of my own in a Rubbermaid jar, it barely lasts the season before it's dark and crusty.

Obviously not keeping the kit climate controlled would shorten the time I trusted it.

 

[Brad_C]

Most of my reagents are > 5 years old. The only things I've found that theoretically may degrade are the CYA reagent and FAS titrant but I haven't had that happen yet. The DPD powder clumps up, but still does the job. I just made a little crusher for the bottle to keep it powdered. Everything else seems pretty stable.

Having said that, it all lives inside in a temperature controlled room that never varies outside of 24-30C year round and tests are done in there, so the reagents are never exposed to natural light or thermal cycles.

 

[Newdude]

it all lives inside in a temperature controlled room

+1. Once in a while it's prefect out and I'll test out at the table by the pool. But 2/3 of my season is cool or hot and any of it may be wet, so the test kit rarely goes beyond the straight line between these two Xs.

 

[Brad_C]

Yeah, nah. My test kit has its own place on the bench with its own mag stirrer. The reagents leave the box, move about 12" to the test area and are returned. The test vials are filled from the pool using a grade A pipette and then I do the tests.

I think I might have a problem. I didn't think I was anal about it until I just re-read what I wrote.

 

[sande005]

I'm very bad. My test kit spends most of the spring/summer/fall closed up, but sitting out in the gazebo near the pool. Protected from rain, and all but very early and late sunlight. But not from the temperature swings. I just buy the refill kit for everything every year. The times I have tested the old stock, all agreed with the new. But since I am a bad test kit owner....why chance it? I'm still feeling like I have tons of money to burn after embracing the TFP methods and saving fortunes in chems and energy. So a few test reagents are a minor expense. One bottle of magic juice from the pool store not bought justifies the expense.

 

[Brad_C]

So a few test reagents are a minor expense. One bottle of magic juice from the pool store not bought justifies the expense.

I think that's a significant difference. A new set of reagents for my test kit is near enough to $200. ($189.10 right now).

That's more than I spend on chemicals on a yearly basis, so looking at the SDS for each chemical I can tell which ones may or may not "age". I have a set of "standards" I whipped up years ago (again, they don't age), so if there's any suspicion I can check the test. The only ones I don't bother with are CYA and FAS titrant, but then again I have 5 year old samples of both that correlate perfectly with reagents I bought last month, so I'll use those until they're done and then move on to the recently purchased ones.

I do have 2 CYA standards I mixed up in 2019, and they still test on-point (well, as much as that test can be).

The biggest saving for me has been reducing the chlorine test from 10ml to 5ml (1ppm resolution). My FC level is generally > 10 so that stretches out the reagents nicely. The only time I ever go back to the original (or even double it for a 0.25ppm resolution) is when doing an OCLT.

To be crystal clear : I'm not advocating against the use of fresh reagents. I'm explaining what works for me and trying to explain why I do it. We in the Southern Hemisphere don't get reagents on-sale, and they're not cheap.

 

[sande005]

If the ~$189 was in AU dollars, that's about $117 US. Currently refills for my kit are $54, and NOT on sale yet (expected to be in the $40+ range). $45 current price for the SeaKlear clarifier that was the last magic juice I bought several years ago. So milage may vary, and therefore the desire to not replace prematurely.

Nice tip about making up your own reference solutions. Any guidance as to how you did it?

 

[Brad_C]

Nice tip about making up your own reference solutions. Any guidance as to how you did it?

Sure. I have a microgram balance and a set of voumetric flasks so I can work in smaller quantities relatively easily. The principles scale however.

Starting with deionised water and whatever powder I was using, I'd dry the powder out on a hot plate, measure it out on the scale and dump it in the water. Transfer the lot to a bottle. Salt was easy as I was aiming for 4600ppm, so 4.6g of salt in 1L. From memory I used un-iodised table salt.

CYA was a bit harder. From memory I had the flask on a mag stirrer for a day or two to make sure it was all dissolved.

I made a 2800ppm solution, divided that by 2 to get a 1400ppm solution and then used a 50ml pipette to take 50ml of that into a 1L flask to give me 70ppm. I still have the 3 bottles (70/1400/2800) which is how I remember the sequence. I *think* after a few experiments 2.8g/l was about all I could get to cleanly dissolve and I was clearly over-egging the desire for accuracy.

I have 2 CYA standards. One just CYA in water and the other is pH balanced, but I would have used bicarb and HCl to ensure it was all "pool compatible". I don't recall why I did that. I did spend a lot of time playing with them trying to read that test reliably. Not a fan of opacity testing.

I did a similar thing with Boric acid, although that was a lot easier to dissolve. I just wanted to be sure I had a firm grip on the borate titration test and since I had the gear it was just another measure/dissolve/dilute.

You don't have to go to the extent I did with the measuring equipment. Larger volumes help compensate for less accurate measuring. If I weighed out 20kg of water on a bathroom scale and I got 92g of salt on a kitchen scale I get ~4600ppm.

CYA would be more of a challenge in a bucket. I'm waiting on some fresh reagent to actually check to see how well the CYA standard has held up, but the salt, hardness and boric acid are all fine.

Memory is a little hazy, that was all done in early 2019 and I've had a bit of stuff going on since then. I've really only had time to get back to it in the last couple of months.

 

[alexmaras]

@Brad_C do you not use Clear Choice Labs for test kits? I'm surprised you're making your own up in Perth, the salt water kit includes standards for 4000ppm salt, 50ppm calcium, 50ppm CYA, 100ppm TA and 7.2pH. Did they not include them way back, or did you run out?

Sounds like you've got the gear to do your own easily too, so I get why you wouldn't buy refills of them too - it honestly sounds like a fun process to make up a tuned standard for your own!

 

[AUSpool]

Without a trustworthy standard or new reagents to compare results it’s hard to know if the results are drifting over time. Home made standards using simple equipment really increases the error factor. I’ve noticed differences in old and new reagents. I abandoned the idea of making a salt standard, it was just too far out no matter how careful I was. If I lived in the US I would go for the annual refil in a heart beat. It’s a small price to pay for confidence in the results. Things are harder to get and cost more in AUS so I’m careful to the point of OCD with my kit and look at getting at least new indicator solutions and the DPD powder every two years.

The reagents don’t degrade at the same rate, here’s an old thread that may be helpful. Should the test kit be replaced each year?

 

[Brad_C]

Do you not use Clear Choice Labs for test kits

I do. I've played with their standards when I first got my kit and decided to make up my own to compliment/replace them.

Home made standards using simple equipment really increases the error factor

My gear is simple, but it has documented accuracy which is adequate for purpose. Back in 2019 when I did the last lot I did actually prepare an error budget for each solution but I can't lay my hands on it now. I was well better than +/- 1 drop of whatever the relevant test reagent was for each test.

It's a bit like filling the test vials using a 10ml pipette. Probably overkill for sample sizing, but then it gets the water from well below the surface, my arm doesn't get wet and I know the sample sizes are accurate to a drop or two (+/- 0.05ml if I'm paying attention).

Like I said before, I'm not advocating for doing what I do. Just explaining what, how and mostly why. If I was in the US and didn't have to pay local prices I'd probably just refresh also, but then how would I justify time in the shed playing with magic colour changing liquids. Keeps the kids amused too.

 

[BMerrill]

I'm in the replace annually camp. Simply purchase the TFtestkit refill when on sale in March.

 

[AUSpool]

I do. I've played with their standards when I first got my kit and decided to make up my own to compliment/replace them.


My gear is simple, but it has documented accuracy which is adequate for purpose. Back in 2019 when I did the last lot I did actually prepare an error budget for each solution but I can't lay my hands on it now. I was well better than +/- 1 drop of whatever the relevant test reagent was for each test.

It's a bit like filling the test vials using a 10ml pipette. Probably overkill for sample sizing, but then it gets the water from well below the surface, my arm doesn't get wet and I know the sample sizes are accurate to a drop or two (+/- 0.05ml if I'm paying attention).

Like I said before, I'm not advocating for doing what I do. Just explaining what, how and mostly why. If I was in the US and didn't have to pay local prices I'd probably just refresh also, but then how would I justify time in the shed playing with magic colour changing liquids. Keeps the kids amused too.

My comment is more about how the average person will perceive the idea of home made standards. I have a glassware set, a range of pipettes and volumetric flasks etc, but the average person might use the kitchen scales but will probably just go with the measurement on the store bought bottle of water, my not even use distilled, add a teaspoon of salt and perfect, think they have a 3000ppm standard. I enquired about a commercial 3000ppm standard which turned out to be +/-100ppm and my lab grade NaCl is +/- O.5% or +/-25ppm.

Measuring small amounts is tricky, I recall a lab prac where about 10 groups all made standards from the same recipe using lab grade balances and glassware and all got quite different results.