Salifert Alkalinity testing approach

[flyfisher2]

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.

 

[happyhourhero]

I just pull the bottom of the pusher up to 1.0 and do the drops accordingly. I’ve used them for years and never had any issues. I don’t generally test my kits against each other because I just care about trends and general ranges.

 

[flyfisher2]

I just pull the bottom of the pusher up to 1.0 and do the drops accordingly. I’ve used them for years and never had any issues. I don’t generally test my kits against each other because I just care about trends and general ranges.

Thats what I've been doing for years as well but I was wondering if the air begins to escape in the syringe after x amount of uses and then the accuracy falls off? Thats why I question the syringe piston method vs a more accurate actual liquid method. I was getting close enough parameters using the Salifert to not worry about it prior to today and then it went totally out of wack.

 

[flyfisher2]

Thats what I've been doing for years as well but I was wondering if the air begins to escape in the syringe after x amount of uses and then the accuracy falls off? Thats why I question the syringe piston method vs a more accurate actual liquid method. I was getting close enough parameters using the Salifert to not worry about it prior to today and then it went totally out of wack.

I just pull the bottom of the pusher up to 1.0 and do the drops accordingly. I’ve used them for years and never had any issues. I don’t generally test my kits against each other because I just care about trends and general ranges.

I do agree with you to a point. Consistency inaccurate as it may be is okay to a point. what if you're trying to achieve a 9-10 dKH and you are consistently getting that with the Salifert but in reality it's a 7.8? sure your consistent but you aren't achieving your goal.

 

[Reef.]

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 black seal should be just above the 1.0ml mark, not on the line but just above it…the air bubble has be bearing on the result, as the air that was in the pink tip is now filled with exactly the same volume of fluid.

 

[kingjames_dc5]

According to the directions the air between the two will not very the results. I say as long as your being consistent with your method and the test results are the same your doing your job in stability.

 

[mdb_talon]

If using the supplied syringe with the tip tightly on the air gap will start around .84.

To your question though i have had the seal go bad basically letting the air in from the back side and distorting the results. So yes it does matter, but if the gap you are getting start at .84 that should be right unless maybe they have sent out some syringes with different size tips, but never seen that myself.

 

[blaxsun]

Yeah, the air does influence the results. I’ve had test kits where the air bubble starts at .82, .84 - all the way up to .90. So it’s very inconsistent, and the exta .02 to .08ml would alter the test result.

I always treat my Hanna tests as the real numbers, because everything else is automatically subject to error and interpretation.

 

[mdb_talon]

Yeah, the air does influence the results. I’ve had test kits where the air bubble starts at .82, .84 - all the way up to .90. So it’s very inconsistent, and the exta .02 to .08ml would alter the test result.

I always treat my Hanna tests as the real numbers, because everything else is automatically subject to error and interpretation.

Lol back to shilling for hannah again? FYI some of the hanna testers(alk for example) also require a syringe and is also subject to error.

 

[blaxsun]

Lol back to shilling for hannah again? FYI some of the hanna testers(alk for example) also require a syringe and is also subject to error.

There are certain test kits where it’s very easy to replicate results time and time again. For example, ones where you have to add x number of drops or a level scoop to a fixed amount of water.

The Hanna 1ml syringes are designed such that when you draw 1ml of reagent you’re actually getting 1ml of reagent, without any air bubbles or anything else to influence the test. This is not the case for most of the other test kits, including Salifert, Aquaforest, Red sea and others.

And yes, I am aware of the whole which curvette side, fingerprints, smudges on vials (etc.) arguments, and while this may every so slightly affect the readings (by a minuscule amount) in some circumstances, the Hanna tests are generally repeatable.

FYI, if I could get a Hanna endorsement I’d be shilling for them even more...

 

[mdb_talon]

The Hanna 1ml syringes are designed such that when you draw 1ml of reagent you’re actually getting 1ml of reagent, without any air bubbles or anything else to influence the test. This is not the case for most of the other test kits, including Salifert, Aquaforest, Red sea and others.

Haha i hope hanna at least gives you a kickback

Just to clarify though. You are saying the syringe on the left(hanna) is foolproof and the one on the right(salifert) is prone to issues? Personally i have had more issues with the hanna style.

 

[blaxsun]

No, I’m saying it’s those infernal tips that are the problem in all of the test kits. The Hanna 1ml syringes have a different kind of rubber stopper than any of the other test kits I’ve used, which makes them more accurate (IMHO) in terms of the amount of reagent drawn.

I think the next titration test I do I’m going to use one of the Hanna syringes, withdraw exactly 1ml and then put the plastic tip on to get the result. Then repeat with the stock syringe/tip using the “air bubble” method and compare results.

 

[Reef.]

No, I’m saying it’s those infernal tips that are the problem in all of the test kits. The Hanna 1ml syringes have a different kind of rubber stopper than any of the other test kits I’ve used, which makes them more accurate (IMHO) in terms of the amount of reagent drawn.

I think the next titration test I do I’m going to use one of the Hanna syringes, withdraw exactly 1ml and then put the plastic tip on to get the result. Then repeat with the stock syringe/tip using the “air bubble” method and compare results.

you can remove the tip, the only reason for the pink tip is it helps with forming drops so the fluid comes out of the syringe more controlled, remove the tip and you will still get the same result.

You will get an incorrect result if you do as you suggest, removing the tip, then filling the syringe, then putting the tip back on, as there will be no air bubble, the air bubble is the same volume as the pink tip.

Test it for yourself, if you have some good scales, 1ml of rodi water weighs 1gram. Fill to the 1ml mark then check the weight.

 

[kingjames_dc5]

So this morning I compared the syringe from an old test and a new test. Found that old syringe liquid level when full to the 1.00 ml mark was at 8.5 and the new at 9.2. I ran two tests one with old syringe and one with new and the results were as follows. 8.5 was 10 dkh 9.2 was 9.8 dkh not much of a difference if you ask me. Both test ran exactly the same from the new test kit.

 

[Snoopy 67]

Pull up until syringe stops.
Push down to 1Ml mark then test.
Repeatable results.
The force used to push the tip onto the syringe will make a minor difference in how much air is pulled in.

 

[flyfisher2]

So this morning I compared the syringe from an old test and a new test. Found that old syringe liquid level when full to the 1.00 ml mark was at 8.5 and the new at 9.2. I ran two tests one with old syringe and one with new and the results were as follows. 8.5 was 10 dkh 9.2 was 9.8 dkh not much of a difference if you ask me. Both test ran exactly the same from the new test kit.

If using the supplied syringe with the tip tightly on the air gap will start around .84.

To your question though i have had the seal go bad basically letting the air in from the back side and distorting the results. So yes it does matter, but if the gap you are getting start at .84 that should be right unless maybe they have sent out some syringes with different size tips, but never seen that myself.

Agree and that’s what I’ve been seing for the most part.8.4
Will conduct a few test tonight and will share my results

 

[flyfisher2]

I just retested same tank using a fresh water sample and these are my results:
With the Hanna I got 7.9 dKH
WIth Salifert bringing black piston tip to 1.0 Ml
I got 0.48 which translates to 8.0 dKH
With Salifert bringing the fluid to 9.6Ml as shown in the picture in the instructions my result was 0.58 which translates to 6.4 dKH
These results refute everything I was experiencing last night and being that I didn’t properly document my results at that time I will chalk it off as user error on my part.
This doesn’t explain how Salifert is getting a 9.6ml Testing Reagant with the plunger tip at 1.0 ml when we agree that the amount of reagant in the syringe is actually or close to 8.4ml

The results obtained today are more than close enough and in line with the results I usually get.

 

[Reef.]

This doesn’t explain how Salifert is getting a 9.6ml Testing Reagant with the plunger tip at 1.0 ml when we agree that the amount of reagant in the syringe is actually or close to 8.4ml

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

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

 

[flyfisher2]

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?

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

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

 

[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.

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.