Which testing kit do I trust?

[Catfish2]

ok, so I have a discrepancy in alkalinity test kits.

Red Sea reads 9.2 dkh
Hanna checker reads 8.1 dkh

Basic question is Which do I trust?

Background:
Red Sea and Hanna were both within a tenth of each other. Then I ran out of Hanna reagent. When I used a new Hanna reagent bottle, alkalinity went from 8.8 on 7/29 to 7.6 the next day 7/30. That was odd so I retested with the Hanna and got 7.5. Red Sea read 8.7 on 7/29 and then 8.4-8.7 the following day on the 30th.

I contacted Hanna and they told me I was storing the reagent at too high of a temp ( high 80's to 90's, when it should be below 77 degrees). They kindly sent me a new bottle. When I checked today the old Hanna reagent read 8.2 and the new reagent read 8.1. Red Sea read 9.2 today.

So it looks like the new Hanna reagent is in line with the old Hanna reagent, but they are one dkh off of the Red Sea. I'm not sure which number to go with. Please share your thoughts.

Complete story:
Red Sea
7/29- 8.7
7/30- 8.4-8.7
7/31- 8.1-8.4
8/1- 8.1-8.4
8/2- 8.1
8/3- 8.4-8.7
8/4- 8.4-8.7 Added 18 frags
8/5- 7.6-7.8 10% water change and started dosing 2 part
8/6- 8.1-8.4
8/7- 8.7-9.0
8/8- 9.2

Hanna:
7/29- 8.8 reagent #1 ran out
7/30- 7.6 retest 7.5 reagent #2 assumed it was defective
7/31- 8/6 no test done
8/7- 8.1 reagent # 2
8/8- 8.2 reagent #2 8.1 reagent #3 (newest reagent bottle just received today)

 

[SPR1968]

I have both as well and they both have margins of error, so to be honest I would use one and stick with it as they are hobby grade test kits and the differences are minimal really.

The Red Sea alkalinity test is very difficult to ascertain the colour change point so there is a certain potential for error there, and the Hanna is +/- 0.03/5% of reading.

I currently stick with the Hanna as it's easy to see the digital read out which was the reason I got it. I also use the phosphate Hanna for the same reason but having said this that's my personal choice and there is nothing wrong with any of the Red Sea kits and I have them all and use them.

 

[Damien Buckley]

I haven't tried the Hanna but the 'new' and improved (black box) Red Sea Pro reagent (which appears to me to be the same as the old standard one that comes with the Marine Care kit) reads over 1dkh different to the previous reagent (white box). The new kit also has an 'over' indicator - it goes from blue to green (reading) to yellow (over) so is much easier to read than before. I wasn't sure about the discrepancy so I contacted ared Sea and they told me how to make a quick & dirty standard solution using Foundation B powder. The new kit was smack on.

Do you have Foundation B? If so I can go back through posts & try to find the calculation for the standard solution - or you can calculate it from the mixing instructions. It's not going to be a lab-grade standard but at least it will give a reasonable indication of which kit is closer.

 

[Martin Kuhn]

Hello catfish2

just by comparing results among different test kits (or different solutions used within) even at different times/days, you won't find out which one is most accurate and if it is accurate enough.
This can only be done by measuring so called refenece solutions and comparing the "measured results" with the ones "printed on the ref.solutions"

 

[Randy Holmes-Farley]

Hanna does sell a standard to check the meter, and there are others available for kits.

I don't know which, if either, is more accurate. Personally, I don't think the difference is all that important. Pick one of the methods and just use it to target a reasonable alkalinity level based on your goals for the tank.

 

[Grey Guy]

I use the Hanna Alkalinity tester. The thing is, if I run the same samples several times, I get quite a large range of results for ppm. Of course the real difference may not be that significant. 50 ppm or so is not that big a difference, unless you are at the bottom or top of the range. Also, the checker only reads up to 300 ppm. All you can tell at that point is that your alkalinity is too high.

 

[Sabellafella]

ok, so I have a discrepancy in alkalinity test kits.

Red Sea reads 9.2 dkh
Hanna checker reads 8.1 dkh

Basic question is Which do I trust?

Background:
Red Sea and Hanna were both within a tenth of each other. Then I ran out of Hanna reagent. When I used a new Hanna reagent bottle, alkalinity went from 8.8 on 7/29 to 7.6 the next day 7/30. That was odd so I retested with the Hanna and got 7.5. Red Sea read 8.7 on 7/29 and then 8.4-8.7 the following day on the 30th.

I contacted Hanna and they told me I was storing the reagent at too high of a temp ( high 80's to 90's, when it should be below 77 degrees). They kindly sent me a new bottle. When I checked today the old Hanna reagent read 8.2 and the new reagent read 8.1. Red Sea read 9.2 today.

So it looks like the new Hanna reagent is in line with the old Hanna reagent, but they are one dkh off of the Red Sea. I'm not sure which number to go with. Please share your thoughts.

Complete story:
Red Sea
7/29- 8.7
7/30- 8.4-8.7
7/31- 8.1-8.4
8/1- 8.1-8.4
8/2- 8.1
8/3- 8.4-8.7
8/4- 8.4-8.7 Added 18 frags
8/5- 7.6-7.8 10% water change and started dosing 2 part
8/6- 8.1-8.4
8/7- 8.7-9.0
8/8- 9.2

Hanna:
7/29- 8.8 reagent #1 ran out
7/30- 7.6 retest 7.5 reagent #2 assumed it was defective
7/31- 8/6 no test done
8/7- 8.1 reagent # 2
8/8- 8.2 reagent #2 8.1 reagent #3 (newest reagent bottle just received today)

You havnt said it but its.very important to test at the same time every single time you test. For instance, my tank is .3dkh higher in the morning then it is at night. Also the hannah checker has a °of accuracy witch maybe around +/- .2 dkh(not very sure but the amount is included on some paper in the checker box). Ontop of that i collect test kits and they all give different readings. Some large jumps, some in range, so unless you buy standards you may never know who to trust. Just have to follow trends, and if i had to follow a trend, it would be with any other alk test kit then the red sea. For some reason the red sea alk kit i feel goes bad after being opened for 3+ months. Just from what ive seen.

Never tryed the new one, but sounds like its the along the lines of the lamotte alk test kit.

 

[Catfish2]

I have both as well and they both have margins of error, so to be honest I would use one and stick with it as they are hobby grade test kits and the differences are minimal really.

The Red Sea alkalinity test is very difficult to ascertain the colour change point so there is a certain potential for error there, and the Hanna is +/- 0.03/5% of reading.

I currently stick with the Hanna as it's easy to see the digital read out which was the reason I got it. I also use the phosphate Hanna for the same reason but having said this that's my personal choice and there is nothing wrong with any of the Red Sea kits and I have them all and use them.

Thanks for the input. Good point, these are only hobby grade kits not multi thousand dollar lab grade tests. I agree the color change can be hard to decipher. I started just calling it when the color first changes rather than wait to get to the endpoint color. Like you, that's why I switched to the digit read out Hanna gives.

 

[Catfish2]

I haven't tried the Hanna but the 'new' and improved (black box) Red Sea Pro reagent (which appears to me to be the same as the old standard one that comes with the Marine Care kit) reads over 1dkh different to the previous reagent (white box). The new kit also has an 'over' indicator - it goes from blue to green (reading) to yellow (over) so is much easier to read than before. I wasn't sure about the discrepancy so I contacted ared Sea and they told me how to make a quick & dirty standard solution using Foundation B powder. The new kit was smack on.

Do you have Foundation B? If so I can go back through posts & try to find the calculation for the standard solution - or you can calculate it from the mixing instructions. It's not going to be a lab-grade standard but at least it will give a reasonable indication of which kit is closer.

Thanks for the info. I didn't know there was a new and old Red Sea test kit.

I don't have the foundation B, but I did order the calibration fluid from Hanna today.

 

[Catfish2]

Hello catfish2

just by comparing results among different test kits (or different solutions used within) even at different times/days, you won't find out which one is most accurate and if it is accurate enough.
This can only be done by measuring so called refenece solutions and comparing the "measured results" with the ones "printed on the ref.solutions"

Good point, I'm not really looking for accuracy, just more precision. The thing I found most odd was that the first bottle of Hanna reagent tested 1.2 dkh higher than the second bottle one day later. I understand that the test kits aren't going to be identical, but I would expect them to be off by relatively the same amount each time.

 

[Catfish2]

Hanna does sell a standard to check the meter, and there are others available for kits.

I don't know which, if either, is more accurate. Personally, I don't think the difference is all that important. Pick one of the methods and just use it to target a reasonable alkalinity level based on your goals for the tank.

I appreciate the input. I did order the calibration fluid from Hanna today. I Agree with the consensus here that testing should be used more to follow trends than to get an accurate level. Close is good enough. The only reason I was concerned was that I'm running an ULNS. ( not on purpose by the way, but my bio load is very low. I just started feeding the corals to try and get nutrients up) So, I'm concerned that with ULN and a possible dkh above 9 ( according to Red Sea) I may be setting myself up for some burnt tips. My goal is 8 and I'm either there or I'm at 9. I guess thats close enough. If see any negative signs I can back off on the dosing a bit.

 

[Damien Buckley]

Thanks for the info. I didn't know there was a new and old Red Sea test kit.

I don't have the foundation B, but I did order the calibration fluid from Hanna today.

No problem. It's literally just landed - I got a black box with a refill I bought last month & a different colour card - get the black box if they have black/white when you buy.

 

[Catfish2]

You havnt said it but its.very important to test at the same time every single time you test. For instance, my tank is .3dkh higher in the morning then it is at night. Also the hannah checker has a °of accuracy witch maybe around +/- .2 dkh(not very sure but the amount is included on some paper in the checker box). Ontop of that i collect test kits and they all give different readings. Some large jumps, some in range, so unless you buy standards you may never know who to trust. Just have to follow trends, and if i had to follow a trend, it would be with any other alk test kit then the red sea. For some reason the red sea alk kit i feel goes bad after being opened for 3+ months. Just from what ive seen.

Never tryed the new one, but sounds like its the along the lines of the lamotte alk test kit.

Excellent point, testing should be at the same time each day. I test at 10:30 pm every night. I don't worry about testing calcium or magnesium at the same time, but it does usually happen at the same time as the alk testing anyway. I don't worry about the timing of the ca or mag testing because they are consummed much slower. Do you think I should make it a point to test those at the same time?

Like I said above, I'm not surprised that the test kits are different from each other. I am surprised that the Hanna reading dropped by 1.2 dkh in one day.

 

[Sabellafella]

Excellent point, testing should be at the same time each day. I test at 10:30 pm every night. I don't worry about testing calcium or magnesium at the same time, but it does usually happen at the same time as the alk testing anyway. I don't worry about the timing of the ca or mag testing because they are consummed much slower. Do you think I should make it a point to test those at the same time?

Like I said above, I'm not surprised that the test kits are different from each other. I am surprised that the Hanna reading dropped by 1.2 dkh in one day.

How are you maintaining calcium and alkalinity? If your using kalk, a calcium reactor or equal parts 2 part, you may not have to keep frequently testing calc or mag. If your alk is steady, they both should be inline with your last test.

 

[Hanna Instruments]

Excellent point, testing should be at the same time each day. I test at 10:30 pm every night. I don't worry about testing calcium or magnesium at the same time, but it does usually happen at the same time as the alk testing anyway. I don't worry about the timing of the ca or mag testing because they are consummed much slower. Do you think I should make it a point to test those at the same time?

Like I said above, I'm not surprised that the test kits are different from each other. I am surprised that the Hanna reading dropped by 1.2 dkh in one day.

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When using our Checkers make sure to follow our 8 Best Practices for Using Your Hanna Marine Checker

 

[Hanna Instruments]

I use the Hanna Alkalinity tester. The thing is, if I run the same samples several times, I get quite a large range of results for ppm. Of course the real difference may not be that significant. 50 ppm or so is not that big a difference, unless you are at the bottom or top of the range. Also, the checker only reads up to 300 ppm. All you can tell at that point is that your alkalinity is too high.

The accuracy statement of the HI755 Marine Alkalinity Checker is ±5% of reading ±5 ppm @25C. If your results were 200 ppm the measure of uncertainty is between 190 ppm-210 ppm CaCo3.

When using our Checkers make sure to follow our 8 Best Practices for Using Your Hanna Marine Checker

 

[jsker]

I have been using the Hanna checker for the past 3 months and trust the Hanna more the Red Sea. I have noticed in the past years tests that I have had large swings between Red Sea test using different reagents.

@Hanna Instruments should we also be cleaning the reagent solution tips after use?

 

[Hanna Instruments]

I have been using the Hanna checker for the past 3 months and trust the Hanna more the Red Sea. I have noticed in the past years tests that I have had large swings between Red Sea test using different reagents.

@Hanna Instruments should we also be cleaning the reagent solution tips after use?

I would be careful to make sure not to have any water in the tip/syringe used for reagents. Its best to keep the syringe/tip for reagent use only. If there was extra DI water or saltwater in the tip after cleaning, then it could be giving you a slightly different volume of reagent which theoretically could impact results. Do your best to get all of the reagent out of the syringe or tip when done with the test. Its best to bring the plunger up/down several times to make sure any reagent droplets are expelled from the syringe.

When you receive new reagents for marine alkalinity, it should come with a new syringe/tip. You want to make to use a fresh syringe/tip with the new reagents.

 

[Breakthecycle2]

I'm in a similar boat. Red Sea .04 Phosphates. Hanna .91. Thats a huge difference.

Red Sea: 4 Nitrates. Salifert ad API 30.

 

[jsker]

I would be careful to make sure not to have any water in the tip/syringe used for reagents. Its best to keep the syringe/tip for reagent use only. If there was extra DI water or saltwater in the tip after cleaning, then it could be giving you a slightly different volume of reagent which theoretically could impact results. Do you best to get all of the reagent out of the syringe or tip when done with the test. Its best to bring the plunger up/down several times to make sure any reagent droplets are expelled from the syringe.

When you receive new reagents for marine alkalinity, it should come with a new syringe/tip. You want to make to use a fresh syringe/tip with the new reagents.

Very good, and thank you for your response