Frustrated with Red Sea test accuracy

[PirateLove]

I test for calcium and mag with red sea. When I draw the liquid into the syringe it is always different. Sometimes it comes out to where I have 1ml bubble others it is 1.5 and it always changes. Just a change in 1ml will change your readings 200 points!

[Scott07]

The bubble at the top of the syringe nearest the plunger shouldn't matter or affect your test results unless you're using more than one full syringe of reagent to get your reading. And even then, unless you have a huge bubble, I think you should be able to use the full 1ml of reagent without getting to the bubble. Think about it this way.... that bubble is there regardless. It's there when you start your titration, and its there when you finish (color change). As long as that bubble doesn't change volume (it doesn't), the only thing that matters is the position of the plunger.

Now what i do worry about are bubbles caught in the middle of the reagent in the syringe. But that's easily remedied by pulling the plunger in/out a few times to purge any air bubbles. Hope this helps!

[NO3]

Go to a LFS and ask to buy a used Salifert syringe. They prob have a ton of them in the back room

[Joe0813]

Bubble shouldn't matter anyway. Just remmeber where you started and watch how much you used

[PirateLove]

Originally Posted by NO3

Go to a LFS and ask to buy a used Salifert syringe. They prob have a ton of them in the back room

What is the difference between the Salifert and Redsea syringes?

[homer1475]

I don't use either. Bought a big box(1k) of 1ml lure loc syringes on amazon for like 10$.

The bubble at the top shouldn't matter. It's there when you draw the liquid in, and there when you end. Just read where the plunger is.

[PirateLove]

I'm pretty sure it does matter. If the bubble is larger there is less liquid. If your liquid is higher or lower in ml's then your going to come out with far different results.

[outssider]

Originally Posted by PirateLove

I'm pretty sure it does matter. If the bubble is larger there is less liquid. If your liquid is higher or lower in ml's then your going to come out with far different results.

you're wrong...….you only count how fare the plunger moves. It doesn't matter the size of the bubble as long as you're not running out of reagent that's in the syringe …..check out some you tube videos....red sea has a bunch of them on you tube.....

[Anemone]

Red Sea takes into account the bubble. If you're getting a different "sized" bubble, then there is operator error. The bubble is equal to the amount of air in the special tip they attach, and it shouldn't change every time.

Kevin

[Xandernfs]

I remove the bubble manually.
-All you have to do is draw up a little bit of liquid (~.4ml) and then flip the syringe over. -Once you've flipped it over, flick the syringe until the bubble has gone to the top (opposite of the plunger).
-Push the plunger down until there is no liquid visible.
-Then dip the tip into the solution to push out the rest of the air and draw up the rest of the liquid until 1ml.

This way you have no bubble to worry about and less room for error.

[bekate]

They are probably not as accurate as chemistry syringes but we learned in Chemistry that the bubble is part of the calibration when they make them.

What really bugs me about the Red Sea tests is that the syringes are really cheap (and even say that they are supposed to be used only once...) so mine are really worn out. Ah well, we'll try a different system after our move....

[Anemone]

Originally Posted by Xandernfs

I remove the bubble manually.
-All you have to do is draw up a little bit of liquid (~.4ml) and then flip the syringe over. -Once you've flipped it over, flick the syringe until the bubble has gone to the top (opposite of the plunger).
-Push the plunger down until there is no liquid visible.
-Then dip the tip into the solution to push out the rest of the air and draw up the rest of the liquid until 1ml.

This way you have no bubble to worry about and less room for error.

If you do this, you are wasting your titrant. Red Sea specifically states the bubble is part of their calibration. If you replace the bubble with titrant, when you push the plunger all the way down, you still have titrant in the tip (rather than air), which you are wasting.

Kevin

[Anemone]

Originally Posted by bekate

What really bugs me about the Red Sea tests is that the syringes are really cheap (and even say that they are supposed to be used only once...) so mine are really worn out. Ah well, we'll try a different system after our move....

Yeah, my Calcium test has no ml lines left above the 0.5 ml point. Makes getting an accurate 1.0 ml fill a challenge.

Kevin

[Xandernfs]

Originally Posted by Anemone

If you do this, you are wasting your titrant. Red Sea specifically states the bubble is part of their calibration. If you replace the bubble with titrant, when you push the plunger all the way down, you still have titrant in the tip (rather than air), which you are wasting.

Kevin

I’ve been putting the titrant back into the main bottle since I only use the appropriate syringe for each test.


Maybe I need to reread the directions?

[Tripod1404]

Originally Posted by Anemone

If you do this, you are wasting your titrant. Red Sea specifically states the bubble is part of their calibration. If you replace the bubble with titrant, when you push the plunger all the way down, you still have titrant in the tip (rather than air), which you are wasting.

Kevin

Not only that, but it would also give wrong results since it was not calibrated to start with 0.4mls of more titrant. Basically, the real amount of titrant used will be different than what is shown on the syringe.

[Uncle99]

You have to follow instructions.
Red SEA is clear to pull up to 1ml, but liquid only goes to .9, the .1 is in the tip.

[Anemone]

Originally Posted by Xandernfs

I’ve been putting the titrant back into the main bottle since I only use the appropriate syringe for each test.


Maybe I need to reread the directions?

How? If you have the bubble, all that is left in the tip when the plunger is fully depressed is air; if you do away with the bubble, you still have titrant left in the tip once the plunger is fully depressed.

Kevin

[2_zoa]

Originally Posted by Anemone

How? If you have the bubble, all that is left in the tip when the plunger is fully depressed is air; if you do away with the bubble, you still have titrant left in the tip once the plunger is fully depressed.

Kevin

A quick cycle with air will purge the syringe.
My issue with putting used titrant back into the bottle, (which Red Sea states not to do) is that the tip has been exposed to the tank water and titration mix possibly contaminating the titrant.


For the thread........
Really, this is being way over thought. There will be an air bubble as mentioned by others and the test should be done before you run out of titrant in the syringe. Thereby negating the air bubble completely. You just read the amount used. Not what’s left.

[Xandernfs]

Originally Posted by Anemone

How? If you have the bubble, all that is left in the tip when the plunger is fully depressed is air; if you do away with the bubble, you still have titrant left in the tip once the plunger is fully depressed.

Kevin

Reread the instructions:

Raise the plunger of the syringe until the bottom ring of the plunger (see arrow in diagram) is at the 1.0 ml mark. The surface of the liquid will be approximately 0.1 – 0.15 ml below the plunger. Do not try to remove the air trapped between the liquid and the plunger. This small volume of air corresponds to the liquid held inside the plastic tip.

Thanks for the heads up Kevin. So now that I know to NOT take the bubble out I won't. But since I have been taking the bubble out, how would that throw my readings off? I'm assuming my reading would be less than what they actually are since I added more titrant?

[homer1475]

Actually I don't think it would matter unless your using the entire syringe.



The bubble is at the top of the syringe, therefore if your only using say 8ml of titrant, that amount won't change, you would just have titrant up to the plunger instead of a bubble. if you used the enitre syringe and needed more, this is where it would throw the readings off because you would be adding titrant instead of the bubble.



IE:
say the bubble represents 1ml. You would be adding 11ml of titrant instead of 10 if using the entire syringe. If your adding 8ml, that amount won't change because you start with the titrant not the air bubble. I think this would be the only time the bubble would make a difference.

[nereefpat]

Originally Posted by homer1475

Actually I don't think it would matter unless your using the entire syringe.

Correct.

The way to think about it is:

You are measuring the amount of fluid used in the syringe, which is the difference between where you started and where you stopped.

[Xandernfs]

If that's the case, I'm going to keep adding the bubble since that's what I've been doing.

[NO3]

This is just my opinion....so plz no piling on

I feel every test on the market...red sea...Salifert....etc..... Only gets you a "range" of what's going on within +/- 5/10%

BUBBLE or NO BUBBLE just gets you a good indicator of "basically what's going on"

As your testing material (solutions/powders) AGES....I feel the test results could even be higher as +/- 10% false reading

Does it reeeeeeeally matter that your test for calcium is 410 but in reality its 390 or 430? I think just knowing its basically in the low 400s is good enough info to base your husbandry on.

So what if your dkh is actually 10.2 but you're testing 9.1 or 11.4.....you know basically where youre at

[Uncle99]

Originally Posted by NO3

This is just my opinion....so plz no piling on

I feel every test on the market...red sea...Salifert....etc..... Only gets you a "range" of what's going on within +/- 5/10%

BUBBLE or NO BUBBLE just gets you a good indicator of "basically what's going on"

As your testing material (solutions/powders) AGES....I feel the test results could even be higher as +/- 10% false reading

Does it reeeeeeeally matter that your test for calcium is 410 but in reality its 390 or 430? I think just knowing its basically in the low 400s is good enough info to base your husbandry on.

So what if your dkh is actually 10.2 but you're testing 9.1 or 11.4.....you know basically where youre at

Yup, just a range, that's all you need, do your tests the same way each tine and be in the ranges posted. It's really not that hard, my 9 year old does it weekly and records on a spreadsheet, tells me only when out of the range...

[homer1475]

Originally Posted by NO3

This is just my opinion....so plz no piling on

I feel every test on the market...red sea...Salifert....etc..... Only gets you a "range" of what's going on within +/- 5/10%

BUBBLE or NO BUBBLE just gets you a good indicator of "basically what's going on"

As your testing material (solutions/powders) AGES....I feel the test results could even be higher as +/- 10% false reading

Does it reeeeeeeally matter that your test for calcium is 410 but in reality its 390 or 430? I think just knowing its basically in the low 400s is good enough info to base your husbandry on.

So what if your dkh is actually 10.2 but you're testing 9.1 or 11.4.....you know basically where youre at

And this is why we tell people a range of acceptable levels, not an exact number. We also tell people not to get hung up on a specific number.