Salifert Alkalinity testing approach

[flyfisher2]

Well unless if there isnt because the seal goes bad, you dont have the tip tight enough, you took the tip out of solution for a second as you pulled, etc. There are countless ways for the seal to be at 1ml yet not have 1ml of solution. Which of course was the whole point of the thread to question what the syringe reading should show when you have the seal at 1ml. If you know what that reading is then you know you actually have 1ml in the syringe/tip.

And that reading for me has been and will continue to be 8.4 in the syringe. Yes the total is 1ml with what ever is in the tip?

 

[flyfisher2]

This chat just got me thinking... I removed the tip and pulled the fluid straight into the syringe. Guess how much fluid it took in? 9.6 ml.
Seems to me that the picture in the instructions showing the plunger black tip at the 1 ml mark may have been done without the pink tip on the syringe.

 

[Ultra Aquatics]

I stopped trusting my Hanna alk checker long ago. There was too much variance between reagent bottles. I use Alkatronic and cross check against Salifert. With the air bubble at 8.4 it has always been spot on. Occasionally the air bubble will end up at 9ish, I will then remove the tip and reattach to get it at 8.4.

 

[Snoopy 67]

That's why you pull up until it stops, past the 1ml mark, any extra air is expelled .
Then push down to 1ml mark for correct amount of solution & start test.
You get a new syringe with every kit, use it.
Like I said previously, how hard you push the tip on the syringe will vary the starting position of the test slightly.

 

[flyfisher2]

That's why you pull up until it stops, past the 1ml mark, any extra air is expelled .
Then push down to 1ml mark for correct amount of solution & start test.
You get a new syringe with every kit, use it.
Like I said previously, how hard you push the tip on the syringe will vary the starting position of the test slightly.

LOL, not sure why anyone wouldn't want to use the new syringe in the new kit. I'm sure we all have pulled the plunger up past the 1ml mark as you recommend and expelled the extra air and with the tip tightly on have arrived at the 8.4 ml or close to that number. Try it and let us know if you get a significantly different result.
What you refer to as how hard you push the the tip of the syringe is basically putting too much pressure and allowing air into the syringe. Yes?

 

[Snoopy 67]

I do get a starting point of close to 8.4 - 8.5
The tip is put on & left on before the 1st use so there is no air being let in.

 

[PatW]

I use Hanna, Salifert and Red Sea Pro. Hanna resolves down to .1 DKH, Salifert to .3 DKH and Red Sea Pro to .2 DKH. Hanna gives an objective result. Salifert and Red Sea Pro use a color end point so deciding on the end point is a bit subjective. But in using all three, I have found that all the tests vary by about the same amount day to day. But Salifert reads about .8 DKH higher than Red Sea Pro or Hanna. However, that is not that important. In order to get a true value, you need to make up a set of standards and calibrate the tests against the standards. I have not bothered. I just use the three tests and I pay more attention to the amount and direction of the change.

 

[WallyB]

I was doing my weekly testing today and noticed unusually high result on ALK using the Salifert test kit. I immediately pulled the Hanna and using the same water sample I obtained the results I expected. I again tested with the Salifert and got the same high results. I went to the graphics in the Salifert instructions and started playing with the syringe.
I noticed that in the picture where Salifert instructs that we bring the piston to the 1.00 ml the fluid level is at .96 roughly?
When I went by the piston method the fluid level was in the 8.4 to 8.5 area and I was getting the high Alk results. ( 9.3 as I recall). When I went for the fluid level at 9.6 my results were 7.9 dKH vs 7.8 dKH on the Hanna.
Have any of you observed similar results and does my method make sense? I've been reading several threads on Salifert testing and didn't come across a direct answer to my simplistic approach. Forgive me if this has already been addressed and I missed it.

The air bubble below the piston is normal (expected) and doesn't affect accuracy.

What is important is the from the Tip up to JUST BELOW the Piston/Air pocket it's all liquid.

Remember when you add drops you are not adding the Air Pocket, you are adding just the liquid from Tip and up.
So that means your result will be accurate if you are drawing in reagent and not creating 2nd air pockets. (To ensure that keep tip below liquid level when drawing regeant, and make sure tip is firmly pushed on, so it doesn't leak in air as you draw regaent.

Another thing I learned when comparing Salifert to for example a Hanna Alk tester is Salifert will be higher than a Hanna by around 0.5 dkH. More if you are below alk 8.0dkh.

Also when looking for the color change from Blue to Pink. I found that the most accurate result is making sure you stir and wait a bit as you start noticing Pink showing up. As soon as the vial changes to almost pink (not purple) and stays (pink) is the most accurate Salifert Alk result.

Best explained by the experts.

https://www.reef2reef.com/threads/c...test-kits-how-do-i-know-when-its-done.376231/

 

[flyfisher2]

I use Hanna, Salifert and Red Sea Pro. Hanna resolves down to .1 DKH, Salifert to .3 DKH and Red Sea Pro to .2 DKH. Hanna gives an objective result. Salifert and Red Sea Pro use a color end point so deciding on the end point is a bit subjective. But in using all three, I have found that all the tests vary by about the same amount day to day. But Salifert reads about .8 DKH higher than Red Sea Pro or Hanna. However, that is not that important. In order to get a true value, you need to make up a set of standards and calibrate the tests against the standards. I have not bothered. I just use the three tests and I pay more attention to the amount and direction of the change.

Would like to read more on the set of standards you refer to.
Care to elaborate or reference for further reading?
Thanks in advance

 

[Reef.]

Okay so the air between the actual 1 ml line and the 8.4 ml is offset by the fluid in the tip which brings total fluid to 1 ml. I stand corrected?

correct.

 

[Reef.]

Well unless if there isnt because the seal goes bad, you dont have the tip tight enough, you took the tip out of solution for a second as you pulled, etc. There are countless ways for the seal to be at 1ml yet not have 1ml of solution. Which of course was the whole point of the thread to question what the syringe reading should show when you have the seal at 1ml. If you know what that reading is then you know you actually have 1ml in the syringe/tip.

Not sure what point you think you are answering here?

I have answered the op and also posted a picture, of course if the equipment is faulty the result will likely not be correct, or if you pull the tip out of the fluid…all common sense, the instructions which I’m sure the op has read says not to do that, again I’m lost on what point you are trying to make.

 

[mdb_talon]

Not sure what point you think you are answering here?

I have answered the op and also posted a picture, of course if the equipment is faulty the result will likely not be correct, or if you pull the tip out of the fluid…all common sense, the instructions which I’m sure the op has read says not to do that, again I’m lost on what point you are trying to make.

Not making a point just addressing the OP actual concerns rather than incorrect and blanket statements that it does not matter the size of the air gap. Now he knows what he was actually asking(that with this syringe the air gap starts at approximately .84 when working correctly)

 

[nereefpat]

In case it isn't clear, and it seems like people are always confused, the instructions on the Salifert alkalinity kit are just fine. You don't need to concern yourself with any bubble by the plunger or the volume in the tip. The bottom of the plunger should start at the 1.0 mark.

The alk in the sample is simply calculated by the amount of acid delivered from the syringe. That amount of acid equals the amount that the plunger moved. So if the bottom of the plunger moved from 1.0 to 0.5, then 0.5 mLs were delivered, and the alk equals 7.7 dKH.

It does not matter that there is a bubble, and it does not matter that there isn't fluid all the way to the top of the syringe. You are only keeping track of how far the plunger moves.

An alkalinity test is, by definition, a titration of how much acid it takes to drop the pH of a sample. For the record, I would always trust a titration like salifert over a colorimeter like Hanna.

 

[Reef.]

Not making a point just addressing the OP actual concerns rather than incorrect and blanket statements that it does not matter the size of the air gap. Now he knows what he was actually asking(that with this syringe the air gap starts at approximately .84 when working correctly)

I have gave a very detailed reply, I have not said the size of the air bubble doesn’t matter, if that is your concern then best quote and reply to that person rather than quote me.

 

[mdb_talon]

Who agrees there’s only 8.4ml in the syringe?

If the black seal is at 1ml then there is 1ml in the syringe.

I have gave a very detailed reply, I have not said the size of the air bubble doesn’t matter, if that is your concern then best quote and reply to that person rather than quote me.

The first quote is why i replied in the first place and clarified that is only accurate if the seal is good/did not suck any air/etc. Not sure why it has you so worked up.

 

[Reef.]

The first quote is why i replied in the first place and clarified that is only accurate if the seal is good/did not suck any air/etc. Not sure why it has you so worked up.

which is a true statement?

So why quote me, if your issue is blanket statements?

As said, I previously replied a very detailed reply to the op., with a picture.

If your point is the syringe could be broken so could give an incorrect reading then yes I’m sure everybody would agree with that

 

[Scorpius]