Old vs New Reagents

[AK-]

I just got new reagents for my test kit and decided to compare with the old reagents I was about to throw out....

~2 Years Old Reagents (23 months)
FC: 15
CC: ~0.5
CYA: - (Out of R-0013)
pH: 7.5
TA: 90
CH: 175

~2 Year Old Reagents (22 months - Never used)
FC: 14
CC: ~0.5

1 Year Old Reagents (12 months)
CYA: 60

Brand New Reagents
FC: 13
CC: ~0.5
CYA: 60
pH: 7.5
TA: 110
CH: 150

Even though I keep my test kit in a temperature controlled dark place (indoors cabinet with nothing else them test kit) and try to minimized exposure to sunlight as much as possible I expected old reagents to perform way worst than they really are.

I wonder if these results are repeatable... I guess I'll be getting new reagents next couple year only to test that. Perhaps even rescue my old TF-100 bottles from the garbage to compare a 3 years old reagent.

Note: None of my old reagents looks degraded

Has anyone tried to compare old vs new reagents year after year?

 

[an1vrsy]

Has anyone tried to compare old vs new reagents year after year?

No…. However, I have a hard time throwing things away. From my original K2006C (purchased when I created my TFP account) those old 2 oz reagents are stored in a plastic bag where I keep my test kit. Mainly not sure how to dispose of the old stuff. Let me run tests on those 5 year old reagents. I’ll post back here tomorrow with the results.

 

[jmastron]

This is my experience too -- my reagents are kept indoors (I test in the kitchen). While I go through the FAS-DPD and pH reagents pretty quickly, I only test TA/CH/CYA/Salt a few times a year (because they're pretty stable and predictable) and never use them up. I've used 4 year old reagents before realizing, and when I got new ones got the same values.

That's not a guarantee, and if I had a new pool or fluctuating values I would want to start with fresh reagents, but I'm willing to take the risk and extend a year or two when retesting the same pool.

 

[sduda210]

I used to buy new reagents every year but, like you, I ended up comparing results with new and old. I decided to hold on to the old bottles. I test FAS-DPD and pH multiple times a week. I end up using amount an entire bottle of the FAS-DPD liquid reagent a year but I get much longer from the powder. I get two years from the 2 oz pH reagent.

Once TA, CH, CYA, and salt are in range I only test them once a month. Even with just monthly testing the CYA reagent gets used up pretty quickly. Since you only use a drop of the chromate indicator for salt, that lasts forever. My 4 year old salt test kit still measures the same salt concentration as my new kit.

 

[AK-]

I used to buy new reagents every year but, like you, I ended up comparing results with new and old. I decided to hold on to the old bottles. I test FAS-DPD and pH multiple times a week. I end up using amount an entire bottle of the FAS-DPD liquid reagent a year but I get much longer from the powder. I get two years from the 2 oz pH reagent.

Once TA, CH, CYA, and salt are in range I only test them once a month. Even with just monthly testing the CYA reagent gets used up pretty quickly. Since you only use a drop of the chromate indicator for salt, that lasts forever. My 4 year old salt test kit still measures the same salt concentration as my new kit.

I used to use a test my FC every other day when I was using LC. That burns thru FAS-DPD reagents pretty quickly. After switching to SWG I test every other day with the OTO to ensure I'm above 5ppm and only use FAS-DPD once a week (or before and after heavy use) to ensure I don't overshoot the FC.

I wish there was a trustworthy pool store with reliable tests where I could take a sample of water and compare the results to see if my reagents are still good... then I wake up and realized that is just an impossible dream.

 

[IceShadow]

I wish there was a trustworthy pool store with reliable tests where I could take a sample of water and compare the results to see if my reagents are still good... then I wake up and realized that is just an impossible dream.

I'd be willing to wager that there are absolutely stores out there that train their people well, keep their devices calibrated, and use proper testing procedures with the equipment, and get results that would be usable to check against reagents. If it were a pressing need, I'd just test my water, then bring it to a few stores and see who's closest, repeating the test every few weeks. If anyone was on each time, I'd have a lot more faith in them.

But there's a lot of variables that can change over the years there, so it'd still be hard to trust it long-term.

 

[duraleigh]

I believe trusting the results of your tests is paramount. At what year do you begin to question them? Year two? Year 4?

It's reassuring to me to manage a $40,000-100,000 investment with the guidance of about $50 in fresh testing material at least every two years.

$25 annually is frittered away on so many LESS IMPORTANT things, the cost savings seems inconsequential to me.

 

[proavia]

Exactly!
And just because your old reagents appeared "good" when compared to your fresh reagents today, tomorrow could easily be different. Personally, I don't want to waste time continuously comparing old reagents to new reagents.

 

[newdude]

I have a large pool so one 20 lb bag of CH or CYA costs 60% more than the refills. I'm not buying $80 bags unless I'm *sure*. It's kinda funny how being cheap keeps me from being cheap here.

 

[AK-]

I wasn’t even considering “saving money” on reagents… I was thinking in the lines of…
1 - Throwing away somethig that still looks good… there is already way too much waste around us.
2 - In an emergency (let’s say a shortage of reagents)…. knowing the limits of old reagents can be the difference between properly managing the pool or not.
3 - Good old curiosity

 

[newdude]

3 - Good old curiosity

This one got me last night thanks to your thread. I went and dug out the TF-100 that was expired when we moved two years ago and has sat on a shelf in my garage since. It's 100+ in the summer and 0- in the winter.

Both sides of the comparator block were off by a few shades.

The fas/DPD powder was black and wouldn't turn the sample pink after I crushed it up. I switched to new fas/DPD and the old R0871 claimed I was 5 FC more than I was.

The blue CH reagent was gummed up in the tip and wouldn't drip. Even if I cleaned the tip, I would have never trusted it anyway so I stopped there

TA and salt were surprisingly good, but again, after the others, I'd have little faith going forward. Going backwards, all we can prove is that they went bad between 1 and 3 years, likely in stages.

I stole 2 of the vials from the old kit and disposed of the rest.

 

[Methuselah]

I suspect there are other concerns as well as just their age. Some of my 1990's kit is still good. However, I did notice opening them (exposing them to air) quickly degraded one or two of the bottles.

The CYA seems to not have any expiration at all, phenyl red stained the bottle a bit if readings didn't closely compare (but could be off by a tenth without that staining), TA chemicals were initially unaffected even though the color change was wrong colors but after a few uses readings became unreliable, and the dpd powder clumped and required a hair more than one scoop but worked just fine and the drops were still good (not much left so no idea if the would have held up).

All were stored indoors in the dark.

My local Leslie's gets CYA testing right, TA pretty close MOST of the time, PH spot on all but once but I've only felt comfortable making decisions using their CYA results. That's for a hot tub, 515 gallons of potential "damages".

FWIW, I also still have some old phenyl red and CYA reagents I'll probably use again, like I said, 515 gallons. That attitude would change if I was maintaining 5000 gallons plus...

I understand not trysting the pool stores results, and certainly not their advice, but suspect their equipment for some of the testing is better than ours. This leads me to believe some of you folks are nuts not to seek out a store they can trust for at least some of the testing. Of course it would be a requirement to watch them doing the testing so that rules me out because my better half drops off the samples. And yes, I understand there's calibration process considerations too...

 

[newdude]

Of course it would be a requirement to watch them doing the testing

There's nothing to watch on the new machines. They used a new puck and syringe for every customer at my place. But did the Bioguard machine really have my best interests at heart ? Did it REALLY ????

Would the store perform daily testing for me at $13 each when I never bought what they reccomended ? Turn down their advice a handful of times and they'll stop giving you the free test.

some of the testing is better than ours

We don't need to be better. We need to be equal and within a tolerance that does not matter. All of the taylor drops are accurate to 1 drop or less. +/- 25 CH does not matter in the least. Kinda like FC, the 600 or the 200 part matters, not the 50 or 75.

 

[Methuselah]

There's nothing to watch on the new machines. They used a new puck and syringe for every customer at my place. But did the Bioguard machine really have my best interests at heart ? Did it REALLY ????

Would the store perform daily testing for me at $13 each when I never bought what they reccomended ? Turn down their advice a handful of times and they'll stop giving you the free test.

We don't need to be better. We need to be equal and within a tolerance that does not matter. All of the taylor drops are accurate to 1 drop or less. +/- 25 CH does not matter in the least. Kinda like FC, the 600 or the 200 part matters, not the 50 or 75.

Agreed on daily needs, but I sent samples for occasional double-checks, or once running out of reagent.

Mostly watching implied seeing a log sheet for at least daily calibrations and as you said clearly not tainting a sample. However, I also suppose the tests I cannot do at home might be worthwhile (i.e. TDS, and perhaps metals)? I'm only suggesting a total dismissal is ridiculous, they cannot get everything wrong. Even I'm right once in a while

 

[newdude]

I'm only suggesting a total dismissal is ridiculous, they cannot get everything wrong. Even I'm right once in a while

Therin lies the problem. There's no way of knowing they got CH right this time, or CYA next time. (Or vice versa). They can be right for most of the tests, most of the time and it still calls the whole thing into question not knowing which of the 6 tests is wrong today.

 

[duraleigh]

they cannot get everything wrong

Why not? How do you know which one(s) they got right?

Virtually everyone on this forum understands the value of doing a job yourself if you want it done best........Testing is no different

 

[Methuselah]

Why not? How do you know which one(s) they got right?

Virtually everyone on this forum understands the value of doing a job yourself if you want it done best........Testing is no different

As I said, it's predominately risk assessment. I'm risking 500 gallons and agree 100% it's an entirely different situation for a pool.

To continue would appear argumentative, so at this point I'll just say if this was a matter of who's right and who's wrong, you are right and I am wrong