Question on Testing Technique with Salifert

[AKL1950]

So, for testing, I have Trident and use Salifert and Hanna for backup testing once a week. For Alk, Hanna is always highest, Salifert middle and Trident lowest. For Ca and Mag, Trident and Salifert with Trident being slightly lower than Salifert.

My question is the technique of using the Salifert tests. It says to add drops, one at a time, until the color changes. There seems to be a window of a few drops in each test where you get a slight color change to when you get a full color change. I tend to keep adding drops till I get a full/positive color change. I think that may be why my Salifert test are always higher versus my Trident test (I also think I might be fudging it with an extra drop to get the result where I want it).

For those that use Salifert, what is your technique? Do you stop as soon as you see a slight color change, or do you keep going to get a full color change? Example would be for Alk, stop when you see a pinkish blue, a blueish pink or when you see a full pink color with no blue tint to it. Those three options can make a difference of about 0.6 for Alk.

Jetson

 

[Rmckoy]

So, for testing, I have Trident and use Salifert and Hanna for backup testing once a week. For Alk, Hanna is always highest, Salifert middle and Trident lowest. For Ca and Mag, Trident and Salifert with Trident being slightly lower than Salifert.

My question is the technique of using the Salifert tests. It says to add drops, one at a time, until the color changes. There seems to be a window of a few drops in each test where you get a slight color change to when you get a full color change. I tend to keep adding drops till I get a full/positive color change. I think that may be why my Salifert test are always higher versus my Trident test (I also think I might be fudging it with an extra drop to get the result where I want it).

For those that use Salifert, what is your technique? Do you stop as soon as you see a slight color change, or do you keep going to get a full color change? Example would be for Alk, stop when you see a pinkish blue, a blueish pink or when you see a full pink color with no blue tint to it. Those three options can make a difference of about 0.6 for Alk.

Jetson

When the colour starts to change I record the result but always try to squeeze a few more drops to see how much it changes if at all .
But if I remember correctly when the colour changes is the measurement value you’re looking for

 

[threebuoys]

I go for full color change, but I always swirl the fluid for several seconds to give it time to react. Generally, I have to add one drop after I notice the color shifting before the full color change occurs.

 

[AKL1950]

When the colour starts to change I record the result but always try to squeeze a few more drops to see how much it changes if at all .
But if I remember correctly when the colour changes is the measurement value you’re looking for

So you’re saying the first indication of color change. I’m thinking I’ve probably been doing this wrong and my Alk and Ca aren’t as high as I think they are. Or maybe better said, they arent as high as I‘ve wanted them to be.

 

[Rmckoy]

So you’re saying the first indication of color change. I’m thinking I’ve probably been doing this wrong and my Alk and Ca aren’t as high as I think they are. Or maybe better said, they arent as high as I‘ve wanted them to be.

I keep mine at 7.5dkh
425 cal
And salinity at 1.026
As my skimmer removes water and sludge I have noticed the ato will over time lower salinity
I rarely ever test mag
And it’s been years since I’ve tested ph

 

[Rmckoy]

So you’re saying the first indication of color change. I’m thinking I’ve probably been doing this wrong and my Alk and Ca aren’t as high as I think they are. Or maybe better said, they arent as high as I‘ve wanted them to be.

For Alk . I generally trust Hanna but will double check often with salifert to confirm accuracy .

 

[juiceguy]

I usually stop adding when the color begins to change, from there it usually will be an extra drop or 2 for full color change.
There will always be discrepancies between different brands, best to take the average of all 3 and work from there unless there is a major difference between any of the results.

 

[ReefJunkie1989]

So, for testing, I have Trident and use Salifert and Hanna for backup testing once a week. For Alk, Hanna is always highest, Salifert middle and Trident lowest. For Ca and Mag, Trident and Salifert with Trident being slightly lower than Salifert.

My question is the technique of using the Salifert tests. It says to add drops, one at a time, until the color changes. There seems to be a window of a few drops in each test where you get a slight color change to when you get a full color change. I tend to keep adding drops till I get a full/positive color change. I think that may be why my Salifert test are always higher versus my Trident test (I also think I might be fudging it with an extra drop to get the result where I want it).

For those that use Salifert, what is your technique? Do you stop as soon as you see a slight color change, or do you keep going to get a full color change? Example would be for Alk, stop when you see a pinkish blue, a blueish pink or when you see a full pink color with no blue tint to it. Those three options can make a difference of about 0.6 for Alk.

Jetson

For me hanna always tests about 0.5 dkh higher than my salifert kit even when I wait for the full color change.

 

[bushdoc]

Answer is simple, buy a Reference Solution or a kit which already have it ( Aquaforest). This way you will know at what color change to look.Here is a description from Aquaforest Alkalinity test: "Observe the color change from green through shades of grey and purple to bright pink. Stop adding more drops when sample changes bright pink"
Salifert test is based on same principles, colors may vary, but you look not at first color change, but when color stabilizes.
My answer is based not only on manufacturers guidelines but I still remember lab practice from my college chemistry course 40 years ago.
I am pretty sure Randy would give you more precise and elaborate answer.

 

[AKL1950]

Answer is simple, buy a Reference Solution or a kit which already have it ( Aquaforest). This way you will know at what color change to look.Here is a description from Aquaforest Alkalinity test: "Observe the color change from green through shades of grey and purple to bright pink. Stop adding more drops when sample changes bright pink"
Salifert test is based on same principles, colors may vary, but you look not at first color change, but when color stabilizes.
My answer is based not only on manufacturers guidelines but I still remember lab practice from my college chemistry course 40 years ago.
I am pretty sure Randy would give you more precise and elaborate answer.

your description is the technique/philosophy I’ve been going on. Keep going till you get the full color change. Plus, as you said, my Hanna, for me, is always .4 higher than Salifert. If I use the average for all three, it usually comes up right close to where the Salifert is. I know it’s all just aquarium test kit quality, but you have to have something to base your Alk and Ca dosing on, so I’m looking for the best guess of the three.

 

[Snoopy 67]

Pictures in the instructions show a full color change as the final result.

 

[Homewrecker]

I would send out an ICP to compare. Its weird bc when I was using salifert for Cal it would be as soon as the color changed, for alk when it was blue.
Hanna was always dead on with ICP and I calibrated my trident to my hanna results(ICP was super far off before with Trident's reading with calibration solution)

 

[stevolough]

A drop or two isn’t a big deal either way as long as you do it the same way every time. All about stability.

 

[Snoopy 67]

Another item that will change results is the powder addition. If you don't level the spoon every time but go by eye the concentration will change.

 

[AKL1950]

I would send out an ICP to compare. Its weird bc when I was using salifert for Cal it would be as soon as the color changed, for alk when it was blue.
Hanna was always dead on with ICP and I calibrated my trident to my hanna results(ICP was super far off before with Trident's reading with calibration solution)

My first ICP test matched all my Trident numbers. It just put more confusion in my head.

 

[Homewrecker]

My first ICP test matched all my Trident numbers. It just put more confusion in my head.

Now that is funky! The only reason I stopped using salifert is because I got two consecutive bottles of alk reagent that were testing a whole point over what the water actually was. That was super frustrating at best

 

[Reefltx]

I’ve been using aftermarket reagents. So I just calibrate my trident with the results I get from salifert kits and have been pretty happy so far.

Alkalinity titration endpoint pH & Salifert endpoint color

TL;DR: The endpoint pH is 4.41, and the endpoint color is that "lavender" color I've been telling people about. Over the years, there have been many threads on R2R and other forums debating a couple of basic details relevant to testing for alkalinity in reef aquaria. One of the most...

www.reef2reef.com

 

[AKL1950]

I’ve been using aftermarket reagents. So I just calibrate my trident with the results I get from salifert kits and have been pretty happy so far.

Alkalinity titration endpoint pH & Salifert endpoint color

TL;DR: The endpoint pH is 4.41, and the endpoint color is that "lavender" color I've been telling people about. Over the years, there have been many threads on R2R and other forums debating a couple of basic details relevant to testing for alkalinity in reef aquaria. One of the most...

www.reef2reef.com

Very good read on the color. That about one drop less than I’m using, which drops about .2 from the Alk number I’m seeing when I get to pink. I like it. Lavender it is.

 

[Icryhard]

So you’re saying the first indication of color change. I’m thinking I’ve probably been doing this wrong and my Alk and Ca aren’t as high as I think they are. Or maybe better said, they arent as high as I‘ve wanted them to be.

Note down the first color change and then note down the full color change values. Take an average of these. That's how I do it when I am not certain.

 

[Randy Holmes-Farley Verified Community Expert]

Note down the first color change and then note down the full color change values. Take an average of these. That's how I do it when I am not certain.

The answer for calcium testing is when the full color change is just arrived at. A partial color change means there is still some calcium bound to the dye.