LaMotte test kit warning - The Planted Tank Forum
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post #1 of 26 (permalink) Old 05-25-2006, 12:23 PM Thread Starter
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LaMotte test kit warning

I finally broke down and got a LaMotte test kit, an Alkalinity test to determine Carbonate Hardness. With CO2 calc's being so critical (if you are pushing it to high numbers), having solid numbers around dKH seemed essential.

I'm happy with the kit overall... the results are quite precise. And I hope reasonably accurate. You can detect in increments of about 1/4 of a degree KH, or smaller. But you do have to really look hard to see the color change when the reagents hit their endpoint. But if you look hard, in good light, you can indeed see it.

But I'm posting this as a warning to other people with this same kit. Or for all I know, this could be a problem with all LaMottes's.

The kit comes with a glass vial to hold the sample to be tested, as do most kits. And like other kits, it's marked on the side with significant gradations in milliliters. But in the case of my kit, the markings appear to be wrong.

You are supposed to test with 5 ml of sample water. And as far as I can tell, 5 ml goes way above the 5 ml line on the supplied vial. Using a dosing syringe to measure out 5 ml, I filled a vial from a Red Sea kit. Then I repeated the process with a vial from an AP test kit. And again with the LaMotte kit vial. In every vial but the LaMotte, the gradations on the vial showed 5 ml of sample water. In the LaMotte it was well above 5 ml. When I used the dosing syringe to remove water until the LaMotte vial read on the 5 ml mark, I removed 0.7 ml.

In all of these cases, I'm reading the bottom of the little curve the water makes in the vial. I believe I remember that from high school chemistry.

But regardless, the AP vial, the Red Sea vial, and the dosing syringe all agree. I'm afraid the LaMotte, while expensive and potentially accurate, is badly flawed in the marking of their vial - which will significantly throw off test results. If I'm doing the math right, it looks like this might produce reading about 15% lower than it should. Not what you would expect from such a kit.

So I'm tossing this out there as a word to the wise. Be aware.

Steve - 33g reef and a 180g planted in need of a re-scape.
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post #2 of 26 (permalink) Old 05-25-2006, 12:38 PM
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Have you contacted LaMotte?
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post #3 of 26 (permalink) Old 05-25-2006, 12:46 PM Thread Starter
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Quote:
Originally Posted by Rex Grigg
Have you contacted LaMotte?
No. Are you suggesting it in the interest of them being aware that they have a quality control issue? I suppose that would be the "good citizen" thing to do...

Thanks. I will. And I'll let you know what they say.

Steve - 33g reef and a 180g planted in need of a re-scape.
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post #4 of 26 (permalink) Old 05-25-2006, 12:48 PM
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I have that test kit too, my vial's code is 0647 and the 5ml line is 9mm from the base of the vial.

I also tested the Alkalinity vial against the tubes I use for my Nitrate test kit which also has 5ml lines and they both were equal when poured into each other.
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post #5 of 26 (permalink) Old 05-25-2006, 12:59 PM Thread Starter
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Quote:
Originally Posted by Gordow
I have that test kit too, my vial's code is 0647 and the 5ml line is 9mm from the base of the vial.

I also tested the Alkalinity vial against the tubes I use for my Nitrate test kit which also has 5ml lines and they both were equal when poured into each other.
Thanks for the post. How did your Nitrate test kit vials stack up against the LaMotte vial measurement?

Steve - 33g reef and a 180g planted in need of a re-scape.
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post #6 of 26 (permalink) Old 05-25-2006, 01:15 PM Thread Starter
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Quote:
Originally Posted by Rex Grigg
Have you contacted LaMotte?
I called Lamotte. Everyone I spoke to was very nice and wanted to know if I wanted them to send me a new vial.

The seemed very interested, were very happy to talk about it. And as I hung up the phone I smiled knowing that not once did someone ask me for the code number of the vial (mine is 0778), nor did they ask the lot number of the kit.

I can only presume that they were interested in making me happy, but not necessarily concerned about fixing the problem.

Steve - 33g reef and a 180g planted in need of a re-scape.
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post #7 of 26 (permalink) Old 05-25-2006, 03:22 PM
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Quote:
Originally Posted by scolley
I called Lamotte. Everyone I spoke to was very nice and wanted to know if I wanted them to send me a new vial.

The seemed very interested, were very happy to talk about it. And as I hung up the phone I smiled knowing that not once did someone ask me for the code number of the vial (mine is 0778), nor did they ask the lot number of the kit.

I can only presume that they were interested in making me happy, but not necessarily concerned about fixing the problem.
They may already have known about the problem and were aware of what lots were affected. I work for a company that does many recalls, so I know how hard it can be. Still, it would have been good for them to ask, to ensure that they have bracketed their lots properly.
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post #8 of 26 (permalink) Old 05-25-2006, 04:06 PM
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thats really wierd i always thought lamottes were like the cadillac of test kits
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post #9 of 26 (permalink) Old 05-25-2006, 04:37 PM Thread Starter
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Originally Posted by SammyP
thats really wierd i always thought lamottes were like the cadillac of test kits
I did to. And the wacky thing is, everything else about the kit appears to be wicked accurate. I'll not belabor it here, but there is no comparison between this kit and my little AP "put in a drop, cover, shake, check color and repeat as needed" kit. Much, much more sophisticated. Appears much more accurate.

The LaMotte person on the phone indicated that they have trouble putting accurate marks on the glass. I'll wager I'm one of many, many such calls.

I bought the kit from marinedepot.com, who sent me a dosing syringe with the LaMotte kit. I didn't order the dosing syringe. I'll wager they are tired of complaint calls about the kits - they are just waiting for the customer complaint call so they can say "That's why we sent you the free syringe!"

Steve - 33g reef and a 180g planted in need of a re-scape.
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post #10 of 26 (permalink) Old 05-25-2006, 07:05 PM
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Quote:
Originally Posted by scolley
The LaMotte person on the phone indicated that they have trouble putting accurate marks on the glass. I'll wager I'm one of many, many such calls.
More likely they have trouble getting vials of a consistent diameter (I bet their marking machine just measures from the top or bottom the same amount for each vial). 0.7 out of 5ml seems quite a way out though!

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post #11 of 26 (permalink) Old 05-25-2006, 09:30 PM Thread Starter
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Quote:
Originally Posted by KevinC
0.7 out of 5ml seems quite a way out though!
And that's coming from a guy that should know!

Put it like this Kevin. On two separate tries, always using the same dosing syringe to measure, 5ml worth filled two other vials (one Red Sea, the other AP) exactly to the 5 ml mark. Those same 5ml measured into the LaMotte put the water so far above the line, there was no reason for debating "measure from the top/middle/bottom of the water surface curve" no matter what you look at. And sucking enough water out to make it read 5 ml was 0.7 both times.

I agree. That's way out - and why I figured it was worth posting.

Steve - 33g reef and a 180g planted in need of a re-scape.
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post #12 of 26 (permalink) Old 05-25-2006, 09:39 PM
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Quote:
Originally Posted by scolley
Thanks for the post. How did your Nitrate test kit vials stack up against the LaMotte vial measurement?
The same, exactly 5ml in both cases but the Nitrate is a LaMotte kit as well.
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post #13 of 26 (permalink) Old 05-25-2006, 10:21 PM Thread Starter
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Quote:
Originally Posted by Gordow
The same, exactly 5ml in both cases but the Nitrate is a LaMotte kit as well.
Interesting... so your problem is just with the vial from the Alkalinity test. That's interesting. It also may be worth noting that it appears to be one of least expensive kits they make (here in the States anyway).

Steve - 33g reef and a 180g planted in need of a re-scape.
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post #14 of 26 (permalink) Old 05-25-2006, 11:31 PM
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Quote:
Originally Posted by scolley
Interesting... so your problem is just with the vial from the Alkalinity test. That's interesting. It also may be worth noting that it appears to be one of least expensive kits they make (here in the States anyway).
No...sorry if I mislead but what I was trying to say is the vial in my Alkalinity kit is measuring fine.
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post #15 of 26 (permalink) Old 05-26-2006, 06:19 AM
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Quote:
Originally Posted by scolley
You are supposed to test with 5 ml of sample water. And as far as I can tell, 5 ml goes way above the 5 ml line on the supplied vial. Using a dosing syringe to measure out 5 ml, I filled a vial from a Red Sea kit. Then I repeated the process with a vial from an AP test kit. And again with the LaMotte kit vial. In every vial but the LaMotte, the gradations on the vial showed 5 ml of sample water. In the LaMotte it was well above 5 ml. When I used the dosing syringe to remove water until the LaMotte vial read on the 5 ml mark, I removed 0.7 ml.
And here was likely your fault... you didn't use a precise known reference to measure your 5 mL of water. I have found that the test tubes that come with the test kits typically marketed for the aquarium hobby are not precise. And neither are the drugstore variety dosing syringes, which you most likely used.

Your post did however prompt me to check the tube in my Lamotte KH kit. I used a Class A 5 mL Measuring Pipette (a precise piece of lab equipment) to measure exactly 5 mL of water. I then dispensed the water into the Lamotte KH test tube. Guess what? The meniscus (bottom part of the curve) hit the 5mL mark on the Lamotte tube exactly.

I also have no problem whatsoever detecting color changes on the Lamotte kits. I find they are quite dramatic and easy to read. Are you holding the test tube over a white surface in a brightly lit area?

I acknowledge that it may be possible that the markings on your Lamotte tube could be off. However, since you didn't use a known precise method of measuring your 5 mL reference, one can't be 100% certain.
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