Just got my new gadget a Taylor Speed Stir. It calculated my clorine at 4ppm while the manual way that I use to do it calculated 16ppm. Does the fact that it spins more affect the numbers? I did test twice with using both the standard method and the speed stir and the results were the same.
Taylor Speed Stir
- Thread starter jasonknox
- Start date
I don't know the answer but sure am waiting to see a post from someone who does. Considering getting one myself. But man, those numbers sure have a heck of an "accuracy" gap just from some shaking.
I am not sure what it is called but it is the test where you put the granuals in 10ml of pool water and it turns red and then you count the drops of 871 solution.
Yeah, that's the FAS/DPD.
Jason, that has to be an operator error of some type.
Once the powder turns the solution pink, I can't see that it matters if your swirl it with your hands, stir it with a spoon, or use the speedstir........it'll take virtually the same number of drops to turn the solution clear regardless of the mixing method.
When you perform the test manually, you are swirling to mix, right?
Mixing is mixing......there's nothing the speedstir can do to introduce a variable into the test......perhaps a drop off or so but certainly not a 4X error.
Jason, that has to be an operator error of some type.
Once the powder turns the solution pink, I can't see that it matters if your swirl it with your hands, stir it with a spoon, or use the speedstir........it'll take virtually the same number of drops to turn the solution clear regardless of the mixing method.
When you perform the test manually, you are swirling to mix, right?
Mixing is mixing......there's nothing the speedstir can do to introduce a variable into the test......perhaps a drop off or so but certainly not a 4X error.
There are a couple of possibilities that can introduce that large of an error in testing.
- Are you leaving the stir bar in the vial when measuring the sample?[/*:m
g8qwc7n] - When manually testing are you swirling between each drop of R0871 or are you adding several drops and then swirling?[/*:mg8qwc7n]
I do swirl after adding the powder. Before I add any drops I make an educated guess as to where my clorine is and add drops to get close and then swirl. For example if I decide that my clorine is 5ppm, I may add 6 drops and then swirl. Based on the color after swirling determines how many dorps I add before swirling again. Once I get to light pink I add one drop at a time swirling in between drops. I know this is cheating but figure that the instructions were for the true beginner who had no idea what their clorine was. Could it be that I am not swirling vigorously enough?
I measure the water before adding the stir bar.
I measure the water before adding the stir bar.
Sorry guys, in my original post I indicated 16ppm it was actually 16 drops or 8ppm. Still a big difference.
Try it again swirling between each drop and see if they match. I have done it both ways and I have never had more than a drop difference.
Just performed both test swirling between each drop and had 7 drops with the speed stir and 9 drops manually. Looks as if swirling between drops is very necessary, if you want accurate results. I quess using the speed stir will eliminate any variations in swirl technique.
Well I am at a loss. I performed the test three different ways all with different results although two methods were within .5ppm which I consider to be OK. See below the test method and results.
Test 1: 10ml of water in the speed stir. Drop in agetator and powder and turn on. While spinning I added drops of 871 until it turns clear.
Results: 10 drops to clear resulting in 5ppm
Test 2: 10ml of water in the cylinder add powder and swirl manually. Added six drops of 871 and swirled, Added 2 drops and swirled three times each, and finally added 1 drop and swirled four times each.
Results: 16 drops of 871 to clear resulting in 8ppm
Test 3: 10ml of water in the cylinder add powder and swirl manually. Added one drop of 871 at a time and swirled between each drop.
Results: 15 drops of 871 to clear resulting in 7.5ppm
Test 1: 10ml of water in the speed stir. Drop in agetator and powder and turn on. While spinning I added drops of 871 until it turns clear.
Results: 10 drops to clear resulting in 5ppm
Test 2: 10ml of water in the cylinder add powder and swirl manually. Added six drops of 871 and swirled, Added 2 drops and swirled three times each, and finally added 1 drop and swirled four times each.
Results: 16 drops of 871 to clear resulting in 8ppm
Test 3: 10ml of water in the cylinder add powder and swirl manually. Added one drop of 871 at a time and swirled between each drop.
Results: 15 drops of 871 to clear resulting in 7.5ppm
I noticed the same thing when I got my speedstir.
My CH went down when using the machine to stir. Almost 20%! And the new number has held consistent through three more CH tests several days apart.
FC also dropped. I filled the vial, added the powder, let it stir a while, added about half the drops. It stopped. Started it again, slowly dripped the rest in. It reads lower than it did swirling manually. And the new FC level has been holding steady, aside from the expected daily drop. Same Chlorine usage in other words.
I trust the speedstir numbers. We had larger versions of it in college chemistry when we were doing titrations, and things were really precise then.
My CH went down when using the machine to stir. Almost 20%! And the new number has held consistent through three more CH tests several days apart.
FC also dropped. I filled the vial, added the powder, let it stir a while, added about half the drops. It stopped. Started it again, slowly dripped the rest in. It reads lower than it did swirling manually. And the new FC level has been holding steady, aside from the expected daily drop. Same Chlorine usage in other words.
I trust the speedstir numbers. We had larger versions of it in college chemistry when we were doing titrations, and things were really precise then.
hawkeye
0
just got mine today i will chime in later on how i like it and how it works...........
hawkeye
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the lights on the speed stir are crazy bright!! i went out at late dusk and this thing light up like christmas tree!! real cool item makes it real easy to get fas-dpd results really accurat......i love it....
Not sure if the batteries that came with mine were old, but within two weeks of using it every day the puck started bouncing around like a rabbit. Finally replaced the batteries and it went back to spinning on the bottom like is should.
Does anyone else use the Speedstir to mix up the liquid for the CYA test? I did and the results seemed pretty accurate.