Reef Chemistry Question of the Day #161 Using a Syringe

[Paul B]

well, believe it or not, this is how its done. if youre doing it differently, youre doing it wrong.

I probably am, but it is fascinating anyway.

(By the way, I am sure Randy is correct.)

 

[beaslbob]

interesting and I dune leanred something.

So I don't have to point it up and squirt out the air?

Thanks

 

[FL_Reefer]

This was a great question Randy, I'm surprised how many people are testing incorrectly. When I started keeping corals it was kind of confusing so I can see how many people get this wrong. (Although it's in the directions of most test kits) I could have used this thread about 5 or so years ago, lol. Thank you for all your time you put in here!

 

[Randy Holmes-Farley]

This was a great question Randy, I'm surprised how many people are testing incorrectly. When I started keeping corals it was kind of confusing so I can see how many people get this wrong. (Although it's in the directions of most test kits) I could have used this thread about 5 or so years ago, lol. Thank you for all your time you put in here!

Thanks, I'm glad you liked it.

 

[cowboy]

Reading Jim wells post u would have to concure I unfurtunatley preform aprox 100-150 titration a day and to round to the nearest tenth is more than adiquat with a .2 increment

 

[TaylorPilot]

So you're telling me I've been OD my kid on baby benadryl by like .25 mL?!

 

[Cory]

I still dont get how there is 2.9ml of liquid when it shows 1.6ml. Lol

 

[Cory]

Ok so to make sure i wasn't hallucinating lol, i got a stringe.

I had the plunger all the way down and drew in 2ml of water. And weighed the water.

Result 1.92g water

Then in did the same but drew in air at the 2ml mark to 4ml of water.

Result 2.10g water

Im confused this must be a magicians trick lol

 

[TaylorPilot]

Look at it this way. The syringe starts out as zero. When you pull the syringe up to say 5ml, it is adding 5ml of volume to the space in the syringe. The liquid is drawn into that space to offset that added volume. The graduation marks on the side don't hold any direct relation to the level of fluid. It shows how much volume you have added to the syringe by pulling the plunger up. Because it is a closed system, that added volume has to be replaced by the fluid. Same thing when you push the plunger back down. The volume inside the system decreases, and since the fluid is at the bottom, it is pushed out before the air. This way, the amount of volume in the tip doesn't matter. Technically, if you look at the picture, if you see where the plunger is, then see where the fluid is, and subtract the difference, that will give you the volume of the tip.

 

[Damon]

Ok, learned something.. I generally didn't use the tips because of this and simply used the syringe alone.

With that in mind, would my way throw my testing results off? In the back of my mind, I'm thinking not, simply because there is no air in the tip(I basically push the plunger up and down to rid the air) a potential tip to throw things off? Or am I all wet?

 

[UNCFAN]

2.2

 

[Randy Holmes-Farley]

So you're telling me I've been OD my kid on baby benadryl by like .25 mL?!

Maybe that's why she sleeps so well.

 

[Randy Holmes-Farley]

Ok so to make sure i wasn't hallucinating lol, i got a stringe.

I had the plunger all the way down and drew in 2ml of water. And weighed the water.

Result 1.92g water

Then in did the same but drew in air at the 2ml mark to 4ml of water.

Result 2.10g water

Im confused this must be a magicians trick lol

Alchemy.

 

[Randy Holmes-Farley]

Ok, learned something.. I generally didn't use the tips because of this and simply used the syringe alone.

With that in mind, would my way throw my testing results off? In the back of my mind, I'm thinking not, simply because there is no air in the tip(I basically push the plunger up and down to rid the air) a potential tip to throw things off? Or am I all wet?

Depends on your level of desired perfection.

Even without a tip, there is air between the zero mark on the syringe and place where water enters it that the syringe attaches to, but it obviously is smaller. That air can throw off the reading IF you fill it with liquid AND dispense it somehow (leaving air in that part at the end of the process).

 

[Damon]

Depends on your level of desired perfection.

Even without a tip, there is air between the zero mark on the syringe and place where water enters it that the syringe attaches to, but it obviously is smaller. That air can throw off the reading IF you fill it with liquid AND dispense it somehow (leaving air in that part at the end of the process).

So I will adjust. Using the tip from now on.. Thank you for this "seemingly simple" question, but one that even I, after 20 years plus of messing with saltwater did not know..

Thank you Randy! [emoji4] [emoji4] [emoji4]

 

[Randy Holmes-Farley]

You're quite welcome.

Happy Reefing.

 

[TaylorPilot]

Maybe that's why she sleeps so well.

LOL, my wife wouldn't agree!

 

[specialk]

This was a great article ... (got to it late in the game here) ...

but one final question to make sure I am right .... If I am using the Salifert Kit for Calcium, then would it make a difference if I do the test and administer the liquid with or withOUT the pink tip at the end of the syringe? (I saw several youtube videos where they do the test and do NOT have the pink tip on the end -- but still getting exactly 1ml of Ca-3 into the syringe)

 

[Randy Holmes-Farley]

The presence or absence of a tip makes no difference to the amount administered, but it does impact the drop size, which can control how precise the reading can be (not accuracy, but precision; 5.01 mL is more precise than 5.0 mL, even if the real value is 4 mL).

That is why syringes for such tests use pointy tips: smaller drop sizes.

 

[specialk]

The presence or absence of a tip makes no difference to the amount administered, but it does impact the drop size, which can control how precise the reading can be (not accuracy, but precision; 5.01 mL is more precise than 5.0 mL, even if the real value is 4 mL).

That is why syringes for such tests use pointy tips: smaller drop sizes.

Ahh ok. Completely understood now! Thanks Amigo!