Accuracy of TFTkits Vials May be in Question...

[sccm_sysadmin]

You guys are measuring with micrometers and cutting with chainsaws.

Do you measure, down to the last gallon, exactly how many gallons are in your pool, and use that in your calculation? Or do you estimate to the nearest 100 or even 1,000 gallons? Do you take rain and evaporation into account? Sunlight? Temperature? Alignment of the planets? Whether or not Mars in in retrograde? Maybe we should take the curvature of the earth into account, and whether or not there's a low-pressure system coming through today.

Do you measure the volume and concentration of every bottle of bleach you put in the pool? Or do you trust that they're exactly 128oz and 10% (or whatever you use)? If not, this entire line of thought is silly because your super accurate/precise requirements for FC measurement get tossed out the window as soon as you dump in a bottle that you thought was 10% and was actually 7%, or maybe 16%.

This is exactly why there are ranges to the "target" FC levels. This isn't rocket science so there has to be a fudge factor. As long as you're above the minimum FC level and below the shock level, you're good. The target levels are certainly something to strive for, but they're also a compromise between a number of factors. High enough to keep the pool clean, low enough to keep from irritating your skin and mucus membranes, and enough of a 'reserve' so that if you miss a dose it won't result in an algae bloom overnight.


Now I return you to your arguments over 1mL of water.

- - - Updated - - -

I found that if you buy a cheap digital scale, 1 mL weighs 1 gram. Weigh your samples and never look at the marks on the vials again.

Welcome to the metric system, where 1mL of water has a mass of 1 gram and a volume of 1 cubic centimeter, and requires 1 calorie of energy to raise it's temperature by 1-degree C.

 

[pooldv]

Welcome to the metric system.

Give us another few decades and we'll catch up with the rest of the world.

 

[sccm_sysadmin]

Give us another few decades and we'll catch up with the rest of the world.

It's a nice thought but if I recall, one of the main holdups is land surveying. Every parcel of land in the US would have to be re-surveyed using metric measurements.

You can't just apply a conversion factor to all the currently surveyed property and call it good, because we don't know the accuracy or precision of the original measurements so you introduce a level of uncertainty that throws the whole thing off.

"This property line is shown to be 145.5-ft. Is that 145.5000-ft or really 145.52-ft rounded down? Did we measure to 10th's or 100th's of a foot?" Which number do you apply a conversion factor to? How precise of a conversion factor do you apply? Do you divide the length in feet by 3.2? 3.3? 3.28084? to get meters? Does it even matter if the original measurement wasn't that precise? Lots of issues.

 

[pooldv]

Yes, maybe so, but we could start taking all new surveys in metric. After all, the U.S. has officially, and legally, recognized the metric system for 145 years and has based the units of its standard weights and measures on metric units for almost 120 years. Europe adopted it in the 1700s shortly after we started using the British system of measurement. It's like the chlorine/CYA relationship and the pool industry, the longer you try to ignore it the worse it gets.

 

[Fingaling]

1ml of pure water weighs a gram... 1 ml of pool water, not so much. We switched to the metric system in Canada without remeasuring everything. Just used metric going forward, although it did almost make a plane crash in the 80s when they filled the fuel in pounds instead of kilograms...

Anyway, knowing a bit about manufacturing, I can tell you that unless you're paying for medical grade manufacturing and supplies, you're not going to get that. Plus or minus 10% is pretty standard for any product that is manufactured. In the medical)/lab field, it's closer to plus or minus 1% (or less in some items).

If you like more accuracy, spend money on good test tubes, or a hospital quality syringe. But if it's all working for you, why bother doing anything different? Honestly the scale and mesuring cup you're using to dose your chemicals is probably not accurate as well. And neither is the package size if you're pouring straight from the container and eyeballing it.

I just like to assume all the measurement errors balance out. Otherwise, you'll go crazy.

 

[mikefamig]

My two cents -

Given the choice to make a vial that measures accurately as opposed to one that does not, why not make it accurate? I understand that some parts of the testing process are out of our control, like measuring the exact amount of water in the pool but why not do each step of the procedure as accurately as possible where and when we can?

I'm happy with the test kits and the vials as they are and am glad to have them. They are indispensable tools in maintaining pool water. But I can't argue in favor of measuring the water sample inaccurately if there is a more accurate way to do it available to me. It's a small amount of error but why not do what we can to control each step of these tests as best as is possible. Two or three small mistakes add up to a big one and it's just as easy to use an accurate measuring device as an inaccurate one.

My instincts tell me that a medical or veterinary syringe might be better than the plastic vials that come with the test kits but maybe not. So if anyone knows of an inexpensive way to measure the sample accurately I for one would like to hear of it.

Mike.

 

[mikefamig]

1ml of pure water weighs a gram... 1 ml of pool water, not so much. We switched to the metric system in Canada without remeasuring everything. Just used metric going forward, although it did almost make a plane crash in the 80s when they filled the fuel in pounds instead of kilograms...

Anyway, knowing a bit about manufacturing, I can tell you that unless you're paying for medical grade manufacturing and supplies, you're not going to get that. Plus or minus 10% is pretty standard for any product that is manufactured. In the medical)/lab field, it's closer to plus or minus 1% (or less in some items).

If you like more accuracy, spend money on good test tubes, or a hospital quality syringe. But if it's all working for you, why bother doing anything different? Honestly the scale and mesuring cup you're using to dose your chemicals is probably not accurate as well. And neither is the package size if you're pouring straight from the container and eyeballing it.

I just like to assume all the measurement errors balance out. Otherwise, you'll go crazy.

Plastic medical and veterinary syringes are only a couple of bucks each. Do you know anything of their accuracy?

Mike.

 

[Holydoc]

My two cents -

Given the choice to make a vial that measures accurately as opposed to one that does not, why not make it accurate? I understand that some parts of the testing process are out of our control, like measuring the exact amount of water in the pool but why not do each step of the procedure as accurately as possible where and when we can?

I'm happy with the test kits and the vials as they are and am glad to have them. They are indispensable tools in maintaining pool water. But I can't argue in favor of measuring the water sample inaccurately if there is a more accurate way to do it available to me. It's a small amount of error but why not do what we can to control each step of these tests as best as is possible. Two or three small mistakes add up to a big one and it's just as easy to use an accurate measuring device as an inaccurate one.

...

Mike.

I have to agree with this. If I know that the Taylor vials (the company that makes the chemicals to test our pools) measure more accurately than xyz's vials, I am going to buy Taylor's vials to measure my water samples to test with Taylor's chemicals. That way I know the only errors are with me, and not my equipment. Of course I am that way with everything. Why settle for "good enough" if I can have the best, even if it costs a bit more. Heck, I bought the Speed Stirrer, the SampleSizer, and the Chemical Standards so that I could eliminate errors where possible. "Exaggeration follows:" I think I spend more on my test kit per year than my chemicals for the pool! LOL

The best news here is that, in this case, xyz is TFTestkits.net, and TFT has an undisputable reputation for customer satisfaction. I have no worries that if there is a problem with anything from this company, they will make it right. If there is a problem with the vial you purchased contact TFTestkits.net and let them know. I am sure they will make it right!

 

[pooldv]

My two cents -

Given the choice to make a vial that measures accurately as opposed to one that does not, why not make it accurate? I understand that some parts of the testing process are out of our control, like measuring the exact amount of water in the pool but why not do each step of the procedure as accurately as possible where and when we can?

I'm happy with the test kits and the vials as they are and am glad to have them. They are indispensable tools in maintaining pool water. But I can't argue in favor of measuring the water sample inaccurately if there is a more accurate way to do it available to me.

People who make vials already make both kinds, very accurate and mostly accurate, they don't cost the same price. The same reason that all cars aren't made to go 0-60 in 3 seconds or get 50 mpg. We could make all cars do both but they would cost more, would that be "better"? Tftestkits could sell a TF-100 for 70 bucks and a TF-200 for 85 or 95 bucks with more accurate vials. Just like chevrolet sells a corvette and a cruz. They chose not to and so did Taylor. There is not a Taylor test kit available with less accurate vials and more accurate vials. Taylor has done independent tests on the TF-100 and said it meets industry standards. So, it is good enough for pool testing.

We have seen tens of thousands of pools successfully maintained with TF-100s used in hundreds of thousands of water tests. There is no need to use a more accurate vial in pool testing because the error rate doesn't create a problem with the pool. I am not aware of any instances where algae is attributable to the sample size of the test being off by 5 or 10%. So, there is no problem to solve here. It is not a problem that the vial measurement is off a bit because it doesn't create a problem with the pool care.

The problem of more or less accurate test vials being available on the market has also already been solved. There are more accurate vials available to you, you just need to shop for laboratory grade scientific or medical equipment if that is important to you.

 

[tim5055]

You guys are measuring with micrometers and cutting with chainsaws.

Do you measure, down to the last gallon, exactly how many gallons are in your pool, and use that in your calculation? Or do you estimate to the nearest 100 or even 1,000 gallons? Do you take rain and evaporation into account? Sunlight? Temperature? Alignment of the planets? Whether or not Mars in in retrograde? Maybe we should take the curvature of the earth into account, and whether or not there's a low-pressure system coming through today.

Do you measure the volume and concentration of every bottle of bleach you put in the pool? Or do you trust that they're exactly 128oz and 10% (or whatever you use)? If not, this entire line of thought is silly because your super accurate/precise requirements for FC measurement get tossed out the window as soon as you dump in a bottle that you thought was 10% and was actually 7%, or maybe 16%.

This is exactly why there are ranges to the "target" FC levels. This isn't rocket science so there has to be a fudge factor. As long as you're above the minimum FC level and below the shock level, you're good. The target levels are certainly something to strive for, but they're also a compromise between a number of factors. High enough to keep the pool clean, low enough to keep from irritating your skin and mucus membranes, and enough of a 'reserve' so that if you miss a dose it won't result in an algae bloom overnight.

Great answer. I was having trouble organizing my thoughts on this issue and here they are. Thanks!

 

[Fingaling]

I don't think there is a problem to correct either. If the markings on your tube are off and you feel it makes a difference, you could easily get a syringe and measure a 10ml mark and draw it on.

As a side note, I did just compare my cylinders with some other measuring tools I have. My chlorine cylinder from tf correlates exactly at the 10ml mark with a syringe for infant Tylenol. Although it was a little off at the 5ml mark. My Taylor cylinder they came with the speed stir was about 5% off at the 10ml mark, with it was spot on at the 25 ml mark. My baby advil syringe read slightly smaller than my baby Tylenol syringe. And my kitchen measuring spoons were waaaay off with each other and with everything else.

I'm off for the summer, so I don't have access to my lab equipment at the moment but I could compare my results with lab quality pyrex. I would probably consider that "more" accurate, but still would have a margin of error.

 

[DIFW]

From my experience compounding medications in the hospital and pharmacy, syringes are only accurate to about half the smallest markings on the syringe. For example a syringe the actually has .1 ML markings will only be accurate to .5 ML. When using syringes the expelled amount will be less the amount that does not leave the syringe. Therefore the smaller amount measured the less accurate as the amount not expelled is a greater percentage of the amount being measured. Accuracy also varies by manufacturer, temperature, human error, etc. This is all understood and is not a major issue when calculating chemo doses so...

 

[GoPokes43]

You guys are measuring with micrometers and cutting with chainsaws.

Do you measure, down to the last gallon, exactly how many gallons are in your pool, and use that in your calculation? Or do you estimate to the nearest 100 or even 1,000 gallons? Do you take rain and evaporation into account? Sunlight? Temperature? Alignment of the planets? Whether or not Mars in in retrograde? Maybe we should take the curvature of the earth into account, and whether or not there's a low-pressure system coming through today.

Do you measure the volume and concentration of every bottle of bleach you put in the pool? Or do you trust that they're exactly 128oz and 10% (or whatever you use)? If not, this entire line of thought is silly because your super accurate/precise requirements for FC measurement get tossed out the window as soon as you dump in a bottle that you thought was 10% and was actually 7%, or maybe 16%.

This is exactly why there are ranges to the "target" FC levels. This isn't rocket science so there has to be a fudge factor. As long as you're above the minimum FC level and below the shock level, you're good. The target levels are certainly something to strive for, but they're also a compromise between a number of factors. High enough to keep the pool clean, low enough to keep from irritating your skin and mucus membranes, and enough of a 'reserve' so that if you miss a dose it won't result in an algae bloom overnight.

...

Just an observation that the size of the pool and concentration of bleach have no impact on determining the concentration at any given time. Like you say, if CL is +/- 15%, no big deal. But, if the CH, TA, pH are also off, then you may have a problem level CSI and not be aware of it.

 

[rkeller62]

I think y'all may need to find a troubled pool to go help with as you clearly have your pools well in hand and trouble free!

Also, given where this discussion has gone, it may be more relevant in "The Deep End"

 

[Jason_Strobel]

The TFTestkit cylinders were upgraded about a year ago to have 1 ml line gradations apart for easier reading. The cylinders are designed to measure the same as Taylor Technologies cylinder (9198) as TFTestkits only uses Taylor reagents. They are not designed to be measured against medical instrumentation. TFTestkits cylinder - YouTube

I got my Kit maybe 4-5 months ago, and i don't have the 1ml lines, just every 5ml

 

[Poolweekender]

Got my kit in May, I don't have the 1 ml lines...however the 1 ml lines are not needed as far as I understand.