How Do YOU Use Your Test Kit Syringe?

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dward0487

I thought it would be interesting to bring up a topic that we're all familiar with -- test kits. Each test begins the same way: you fill up your vial/bottle with a given volume of tank water, right? But interestingly enough, I have yet to see a set of test kit instructions that tell you how to use the little syringe that comes with the kit. A lot of kits use a syringe with a cone-shaped plunger, and it seems easy enough to use, but I'm willing to bet that there's a fair amount of variation with regard to how we use them. I'd like to find out how you guys measure your volume in these syringes. I've heard people talk about 3 different methods, so I'm depicting them below:

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Method 1 consists of placing the tip of the cone-shaped plunger at the desired mark, with the water completely filling the syringe.

Method 2 consists of placing the base of the cone-shaped plunger face at the desired mark, with the water completely filling the syringe.

Method 3 consists of creating an air gap between the plunger and the water, and bringing the water level up to the desired mark.

I've heard different people saying each of these 3 methods is correct, but I have yet to see any definitive answer from a kit manufacturer. If you have, let me know! In the meantime, which method do you use?
 
It really depends on weather or not there is a needle or applicator on the syringe. If there is then you will have the air gap present as seen in option 3 , but the plunger will still need to be in the location seen in option 2. The reason for this is because the air gap under the plunger is equal to the quantity of fluid residing in the applicator.
 
What about the water sample Cuvettes that come with the test kits? I have been told The skin of the water sample that forms a curve (like a smiley mouth), the bottom of the curve should meet the 10ml line OR Do you fill the cuvette so that the top of the curve(waterline) meet the 10ml mark
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I'm wondering now does it make a difference in the test results when you do it either way?

If so then we need to take this posting and lock it into useful tip and/or testing information or getting started with saltwater for newbies and oldies alike.
 
I don't remember which one, but I think one of my test kits say to use method one. Also, for the cuvettes, I have read several posts saying they are not right. Some people use a syringe to measure their sample.

I just got the alk tester from Hanna and I found their syringe to be strange. They wanted 1ml but the syringe actually started at 1ml at the bottom of the syringe and counted down to 0. Never had seen that before. My wife is a science teacher and she said she had never seen one like that either.
 
Method 2 for the syringe and then I use a syringe to measure the amount of water that needs to go in the test tubes. Good topic!
 
I don't get why the Test kit manufacturers aren't more clear....I guess it's clear to the scientists that come up with the test kits....
 
@zaphod1 wrote:
I'm wondering now does it make a difference in the test results when you do it either way? said:
It should make a difference, as any method that deviates from the method for which the syringe was designed will result in more or less water being taken up into the syringe than desired. If your initial volume of tank water is off, the results should be somewhat different than the true value.

I actually just spoke to a lady in Customer Support at Red Sea, and she told me in great detail that the proper method for their syringes is Method 2. For their kits, you're supposed to push the plunger all the way to the bottom, draw up your water so that the water is fully touching the black plunger, and bring the base of the plunger face (the first point at which the plunger contacts the side of the syringe body -- not just the tip of the cone) to where it's even with the desired mark on the syringe. I sent an email to Elos Customer Support to determine if this is the method that they recommend, or if their method is different. I will post the answer when I hear back from them.

I hope this helps people!
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Method 2 when drawing water for samples.

Method 3 when using the syringe with the needle.

And for the vials, definitely along the meniscus with the line
 
http://www.reefcentral.com/forums/showthread.php?t=1333391 - Elos recommends 3. Others may differ, but that is their methodology for drawing water into the syringe for their test kits. Vial markings are historically inaccurate. Yes, there will be slight different readings, but the question is not if they will be different, but if the difference is significant enough. There were other threads about differences in readings using the different methods, there are slight differences such as 25-50ppm on MG test kits etc. 25-50ppm difference on the water draw compounds onto the built in variations on sensitivity too. The typical MG test kit is going to have an error rate of 25-50 already based on the reagents used so with the draw variances you may get even more. 50-100 on MG is not that significant if you aim for 1400MG. You can be high or low 100ppm and its not material. Alkalinity/Ca etc have a lower variance rate, but 10% +/- can be of a bit of a concern. In the end, the difference in water volume won't be that big of a deal, its the reagent that is most critical.

In the end... either method is fine so long as you are consistent with it. Once you are consistent with your methods of testing, your numbers will be stable in testing so you can make adjustments as needed.

.5 dkh if you are maintaining a solid 8-10dkh wont matter.
25ppm calcium when are maintaining 425-450 wont matter.
50-100ppm when you are maintaining 1400 on MG wont matter.

Don't fall into the number trap, you want stable numbers with the understanding the exact number will have an error built in. Aim for consistent test readings and methodology and a reasonable middle ground for your numbers. Chasing the accuracy dragon will just drive you nuts and is not critical to your success. Learn to read your tank, your corals and you'll have a much happier existence.
 
I believe most test kit instructions suggest method 3, altough I would not think it affects results, it just takes more time to use the other methods.
 
@TexAgReefer wrote:
Method 2 when drawing water for samples. Method 3 when using the syringe with the needle. And for the vials said:
The syringe with the needle always bothers me. You push the needle onto the syringe but it doesn't go all the way onto the syringe. Is this normal or do I try and force it so the top part of the needle is making contact with the bottom of the tube part of the syringe.
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@Opus wrote:
[I]@TexAgReefer wrote:[/I][quote="Method 2 when drawing water for samples. Method 3 when using the syringe with the needle. And for the vials said:
The syringe with the needle always bothers me. You push the needle onto the syringe but it doesn't go all the way onto the syringe. Is this normal or do I try and force it so the top part of the needle is making contact with the bottom of the tube part of the syringe."]

Most kits that use a syringe for reagent include the needle in the volume of reagent and the line in the body of the syringe is accurate with the proper tip used. If you are using fluid reagents, use method 3 and the proper tip that came with the test kit and your volume will be accurate. Do not mix and match tips from other kits as they may use different sources so the volume may be off.
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I always thought the bottom of the meniscus at eye level was correct. From my understanding the plungers are supposed to be shaped to include the plunger. In a proper syringe the first mark should be placed to include the "needle" and the plunger should be shaped to fit the meniscus therefore the lowest point on the plunger should sit on the desired mark. But I'm no expert...
 
@DaveJ wrote:
[I]@Opus wrote:[/I][quote="[I]@TexAgReefer wrote:[/I][quote="Method 2 when drawing water for samples. Method 3 when using the syringe with the needle. And for the vials said:
The syringe with the needle always bothers me. You push the needle onto the syringe but it doesn't go all the way onto the syringe. Is this normal or do I try and force it so the top part of the needle is making contact with the bottom of the tube part of the syringe."]

Most kits that use a syringe for reagent include the needle in the volume of reagent and the line in the body of the syringe is accurate with the proper tip used. If you are using fluid reagents, use method 3 and the proper tip that came with the test kit and your volume will be accurate. Do not mix and match tips from other kits as they may use different sources so the volume may be off."]

I am using the syringe and needle that came with the kit. If you are not pushing the needle on to the syringe to the correct location, you could pull in too much or not enough reagent. Since there are no directions other than "put the needle on the syringe" I have no idea if it is on there correctly.
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@DaveJ wrote:
http://www.reefcentral.com/forums/showthread.php?t=1333391 - Elos recommends 3. Others may differ said:
Agreed all the test kits and probes are hobby level. Not scientific measuring devices. Just do things the same all the time and be in a range not a specific number and things will be fine. So in short i didn't vote because there wasn't an I'm over thinking it choice.
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