Important findings according how to store open bottles of the reagent for Hanna Marine alkalinity checkers

[gbroadbridge]

The inconsistency of the Hanna alk checker was stopping me buying this checker, I have the nitrate and p04 and rate them, your fridge tip may just push me over the edge to buy one!

Salinity, I use Randy’s DIY method, all you need is plain table salt and a set of 0.01g scales at around $15, then you can make a reference solution as many times as you wish, and know it’s correct.

Yes!

And I use Randy's DIY Alkalinity test to check the accuracy of the Hanna Alk each time I open a new reagent bottle.

My recent new bottle is reading 0.4dKh high, which is the worst yet.

A DIY Alkalinity Test

Alkalinity is one of the most important measurements that a reef aquarist can make. It can become rapidly depleted in many aquaria, requiring frequent measurement in order to maintain stable levels. While hobby test kits for alkalinity can be...

www.reef2reef.com

 

[Jeeperz]

Yes!

And I use Randy's DIY Alkalinity test to check the accuracy of the Hanna Alk each time I open a new reagent bottle.

My recent new bottle is reading 0.4dKh high, which is the worst yet.

A DIY Alkalinity Test

Alkalinity is one of the most important measurements that a reef aquarist can make. It can become rapidly depleted in many aquaria, requiring frequent measurement in order to maintain stable levels. While hobby test kits for alkalinity can be...

www.reef2reef.com

My problem is pH checkers don't stay calibrated and the probes go bad regularly, at least the Hanna ones do. Even when cleaned with probe cleaner and stored in storage fluid

 

[gbroadbridge]

My problem is pH checkers don't stay calibrated and the probes go bad regularly, at least the Hanna ones do. Even when cleaned with probe cleaner and stored in storage fluid

This is what I use. I gave up on cheap Hanna pH meters for the same reasons you stated.
The Milwaukee pH meter hardly moves on calibration.

 

[Opus]

same but I use API kh test I hope it's the same stuff lol

I don't think it matters for API. I use that as my main tester and a bottle will last me 6 months or more and a new bottle is always the same as the old bottle I was using. I'm sure there is some change but it is within the accuracy of the API tests.

 

[Opus]

My problem is pH checkers don't stay calibrated and the probes go bad regularly, at least the Hanna ones do. Even when cleaned with probe cleaner and stored in storage fluid

I haven't tested PH on my tank in probably 20 years.

 

[Lasse]

The inconsistency of the Hanna alk checker was stopping me buying this checker, I have the nitrate and p04 and rate them, your fridge tip may just push me over the edge to buy one!

At least - it has work for me and nowadays I trust this meter. I have never seen any inconsistency between a serie of test done after each other - only that after a couple of weeks test against a new bottle or another method - it is to low. I have use the refrigerator trick for nearly 8 months now and nowadays I can use the reagent to the last drop

I haven't tested PH on my tank in probably 20 years.

He does not use the pH meter for the tank - he use it in order to determine KH

Sincerely Lasse

 

[vahegan]

Thanks for sharing this with us, Lasse. I have been using the shaking before each use method and I have had a significant difference. Unfortunately it did not come to my mind to test the same water with the old and the new reagent, but my reading was 9.4 dKH last week, and 11.5 dKH in less than a week, and I don't think there could be almost 2 dKH swing in my tank. As I have just opened the new bottle, I am now storing it in the fridge. Will be more clever to test the same water with the old and new reagent when the bottle is close to finish. I will report back but t may take a while as I usually test once a week. I hope this method will help me get more consistent results with Hanna's meter.

I am a bit surprised though why this method should work. I think that Hanna's reagent is a mixture of some acid and a die which changes color depending on pH. When we add 1ml of the reagent to 10ml of tank water, the added reagent is sufficient to neutralise the buffering capacity of the water sample and the amount of superfluous acid will change the pH and color of the solution. So, the only explanation for the reagent premature expiration is that probably the reagent evaporates and gets more concentrated, hence lower reading with the old reagent. Then storing the reagent in the fridge would reduce evaporation. I cannot think of a better explanation for this effect. Any other ideas?

 

[gbroadbridge]

Thanks for sharing this with us, Lasse. I have been using the shaking before each use method and I have had a significant difference. Unfortunately it did not come to my mind to test the same water with the old and the new reagent, but my reading was 9.4 dKH last week, and 11.5 dKH in less than a week, and I don't think there could be almost 2 dKH swing in my tank. As I have just opened the new bottle, I am now storing it in the fridge. Will be more clever to test the same water with the old and new reagent when the bottle is close to finish. I will report back but t may take a while as I usually test once a week. I hope this method will help me get more consistent results with Hanna's meter.

I am a bit surprised though why this method should work. I think that Hanna's reagent is a mixture of some acid and a die which changes color depending on pH. When we add 1ml of the reagent to 10ml of tank water, the added reagent is sufficient to neutralise the buffering capacity of the water sample and the amount of superfluous acid will change the pH and color of the solution. So, the only explanation for the reagent premature expiration is that probably the reagent evaporates and gets more concentrated, hence lower reading with the old reagent. Then storing the reagent in the fridge would reduce evaporation. I cannot think of a better explanation for this effect. Any other ideas?

AFAIK, Hanna do not disclose details of how their test works, but I would suggest oxidation of the dye or other components of the reagent on exposure to oxygen, which would occur faster in warmer temperatures.

 

[Lasse]

I am a bit surprised though why this method should work. I think that Hanna's reagent is a mixture of some acid and a die which changes color depending on pH. When we add 1ml of the reagent to 10ml of tank water, the added reagent is sufficient to neutralise the buffering capacity of the water sample and the amount of superfluous acid will change the pH and color of the solution. So, the only explanation for the reagent premature expiration is that probably the reagent evaporates and gets more concentrated, hence lower reading with the old reagent. Then storing the reagent in the fridge would reduce evaporation. I cannot think of a better explanation for this effect. Any other ideas?

I really do not know how it works. I can see two major things - it really slow down some processes or I have been lucky to get at least 3 reagents that have been stable

I probably want to exclude evaporation because it would probably mean a rising result with time

AFAIK, Hanna do not disclose details of how their test works, but I would suggest oxidation of the dye or other components of the reagent on exposure to oxygen, which would occur faster in warmer temperatures.

This or bacterial breakdown of the dye makes more sense for me. But I do not know.

Sincerely Lasse

 

[Doctorgori]

gheez, I lost a LOT of corals from a bad batch of reagent. Thanks for posting this. Should be a sticky

 

[Reef.]

Do you have a link to the DIY method

Here it is, just pick your method for testing salinity, then follow the instructions for making the solution.
It’s very important to measure the salt and water accurately, if you are a little nervous just double or triple the ingredients and that will help reduce any inaccuracies when you’re weighing the salt and water.

http://reefkeeping.com/issues/2004-06/rhf/index.php

 

[kenbennedy]

Do we think my open bottle from the past few months is already damaged/corrupted/oxidized or whatever? Is there any point putting it into the fridge now, or should I just start a new bottle?

 

[Reef.]

Do we think my open bottle from the past few months is already damaged/corrupted/oxidized or whatever? Is there any point putting it into the fridge now, or should I just start a new bottle?

I would say it’s likely pointless, tho I would not throw it away yet, buy a new bottle, then test them side by side.

 

[kenbennedy]

I would say it’s likely pointless, tho I would not throw it away yet, buy a new bottle, then test them side by side.

Great Idea, I do have an unopened bottle ready to go…

 

[vahegan]

I probably want to exclude evaporation because it would probably mean a rising result with time

Evaporation would mean you are adding more acid in the 1ml reagent you add to the water sample. And more residual acid after neutralising the KH, i.e. lower KH reading.
This hanna test is different from titration tests as here you add a fixed amount of reagent and check the resulting pH, whereas in titration tests you check the amount of acid added until a desired pH is reached. Hence the effect of evaporation resulting in more concentrated reagent should be opposite. However, this depends on what acid they use in the reagent. If it is something volatile (such as hydrochloric acid), then it will evaporate from the reagent making it more dilute... Strangely enough, Hanna does not have any warning message about the acid content on the KH reagent bottle (on the Nitrate test sachet, for example, they have a warning "contains malonic acid").

 

[vahegan]

Great Idea, I do have an unopened bottle ready to go…

Please do share with us the result you would get from the old bottle and the new bottle.

 

[atoll]

Here it is, just pick your method for testing salinity, then follow the instructions for making the solution.
It’s very important to measure the salt and water accurately, if you are a little nervous just double or triple the ingredients and that will help reduce any inaccuracies when you’re weighing the salt and water.

http://reefkeeping.com/issues/2004-06/rhf/index.php

Thanks for that.

 

[DxMarinefish]

Thanks @Lasse for this tip.

 

[Reef.]

From the above link, the diy method if using a refractometer 3.65g table salt mixed in 96.35 rodi water.

If using a hydrometer it’s 6.20g table salt mixed in 161g rodi water. Using a 500ml measuring cylinder you would need to multiply the salt and water by 4 to get the 500ml to float the hydrometer, a swing arm hydrometer would require less.

 

[hotdrop]

I have also found that when i get to the bottom of a bottle I start to see wired results. Good to know