Salifert Alk test question

[surf&turf]

So who uses the pink tip on the end of the syringe when they do their test?

 

I have noticed the reading is always higher when I use the smaller tip.

[hypertech]

How could it make any difference? If you put in big drops or little drops, you still need to add about the same amount of regent to get the reaction. Its a titration not a drop wise test.

[surf&turf]

How could it make any difference? If you put in big drops or little drops, you still need to add about the same amount of regent to get the reaction. Its a titration not a drop wise test.

 

I know, but it does.

 

I've tried it both ways, and with the pink tip on, it always tests higher.

 

 

 

[Dr.eclipse]

i use the pink tip. the directions say to do so.

[zygote2k]

I haven't been using the pink tip for years. I throw them away when I get new kits every few months. Consistency is what you are after.

[surf&turf]

I haven't been using the pink tip for years. I throw them away when I get new kits every few months. Consistency is what you are after.

 

 

That was my thinking to, but thought it was odd it would make a difference.

[Jon Lazar]

How different would your results be if you run the test multiple times in a row with the pink tip, and several tips without the tip?

 

Maybe the difference results you observe between using the pink tip or not is due to the precision of the test, or some other factor.

[rocko918]

i dont use the tip either. One of the tips i got did not hold the regent in it. it would just leak out so i stopped using them.

[surf&turf]

How different would your results be if you run the test multiple times in a row with the pink tip, and several tips without the tip?

 

Maybe the difference results you observe between using the pink tip or not is due to the precision of the test, or some other factor.

 

I have done this. Pink tip always tests higher and the results are always very close.

 

Also tested the standard solution without the tip and it was spot on.

[BowieReefer84]

Maybe get someone with a Hanna Alk checker to compare your results against?

 

But as Rob said consistency is key.

Edited June 8, 2012 by BowieReefer84

[Steve175]

IME, the tip makes it easier for the drops to separate. I use the tip, but first I fill the syringe (without it) half full, then put the tip on, and then burp all of the air back into the container, and then fill the syringe to the 1.0cc mark through the pink tip. I think that your error might be because you are adding the tip (full of air) after the syringe is full and therefore over-estimating the amount of reagent you add (likely by the volume of the syringe tip which is ~ 0.1cc). BTW, I have both Salifert and Hanna for Alk and Hanna blows (much less reproducible results).

[hypertech]

You should leave the tip on when filling the syringe. Ignore the air and read the plunger.

[surf&turf]

IME, the tip makes it easier for the drops to separate. I use the tip, but first I fill the syringe (without it) half full, then put the tip on, and then burp all of the air back into the container, and then fill the syringe to the 1.0cc mark through the pink tip. I think that your error might be because you are adding the tip (full of air) after the syringe is full and therefore over-estimating the amount of reagent you add (likely by the volume of the syringe tip which is ~ 0.1cc). BTW, I have both Salifert and Hanna for Alk and Hanna blows (much less reproducible results).

 

Yes, that's probably it. I fill the syringe without the tip.

 

Going to do a test....

[surf&turf]

Ok,

 

Pink tip on will filling syringe, no burping. 8.3

 

No tip, 8.9

 

Pink tip on after filling syringe 9.3

 

Guess I'll stick to no pink tip.

[surf&turf]

I guess this is a Duuh.. moment for me, I should have thought of the extra reagent to fill the tip.

[hypertech]

As long as the tip is on when you fill the syringe you dont have to worry about the volume in the tip.

 

Ignore the air and read the plunger.

[surf&turf]

As long as the tip is on when you fill the syringe you dont have to worry about the volume in the tip.

 

Ignore the air and read the plunger.

 

Thanks, if I use the tip, I'll put it on for the entire process.

[Steve175]

Maybe U an just anal-rententive, but air is compressible and the bubble (without the burb) is a bit variable in size. The burp adds 2 seconds to the process, and make a difference IME.

[ctenophore]

On mine, the air in the tip causes the fluid to start at the .8ml mark (plunger at 1.0ml). So I know that the air is not compressed when I start with exactly .2ml of air in the syringe. This gives a reproducible result within .1 DKH, IME.

[Marc Weaver]

If they based their charts on the amount of titrant used instead of the amount left over in the syringe this problem would go away.

[Marc Weaver]

I did a few alk tests tonight:

 

Salifert with pink tip: 10.5

Hanna Checker: 186ppm (10.42)

Lamotte 4491: 185ppm (10.36)

 

Salifert without pink tip at all: 10.0 (.35mL left)

 

They are all well within the acceptable range of each other, except without the pink tip. The Salifert fluid line with the tip on was at .8mL as it always is with the plunger at 1mL. When I took the tip off, the fluid level was at .95mL and the drop size is much larger which I believe kills the accuracy somewhat. Based on my findings I am sticking with the pink tip on at all times and .2mL of air in the syringe.

 

For what it's worth, I tested the salifert reference solution with the hanna, and it was dead on. I have never had a test that did not make sense to me with the checker, and I'm on my 5th bottle of reagent (around 110 tests so far.) My tank reads from 183 to 187 ppm every time I test, which is 10.25 to 10.48 dKH. I'm dosing 2 part with a dosing pump, 80mL a day of alk and calcium.

[hypertech]

If they based their charts on the amount of titrant used instead of the amount left over in the syringe this problem would go away.

 

I don't see how this would matter other than making the test harder with more steps.

 

Since you are putting a fixed amount in the syringe, you can easily convert the chart to amount used instead of final reading if you want.

[surf&turf]

Maybe U an just anal-rententive,

 

This is probably true.

[Steve175]

Actually I am anal-retentive [my typo above should have read "Maybe I am just anal-retentive"/apologies if my fat fingers made it seem that I was referring to someone other than myself] (And a bit proud of being anal-retebtive ) And a biochemical engineer. [While the thought of titrating reagents with air in the pipette makes me shudder a bit, to each their own.]

I do agree that the actual value matters not so much (within the 8-11 range). Doing the test similarly each time is what really matters to document Alk stability - bubble or not, pink tip or not as long as it is done the same way test-to-test.

 

I was a big fan of the Hanna Alk at first (have had it for 2 years). After ~ 1 year and always being very careful with the vials (rinsing with RODI water after each use, etc) I started getting a random value here and there which was 0.5-1.0 higher than it should have been - confirmed by 2 subsequent Hanna checks verified against Salifert. Plus I hate cutting the little packets and trying not to lose any reagent. Salifert, for me, is quick and almost never needs to be repeated for a suspicious result. I do love Hanna for PO4 though.

 

$0.02

[Marc Weaver]

Steve-

 

The new reagents for hanna alk are liquid and come with a syringe with a tip included, and measure very differently with or without the tip on the syringe. Just thought you guys might get a chuckle out of that.