Method SN aquarium purity testing

[jgm63]

This is based on @jake3d 's write up, but aims to get results around the *middle* of the test range.
When we get results at the edge of the range, eg the max, it may leave us questioning the accuracy, eg was the true value higher than the max (eg due to a mistake with the test method), but can't be detected by the test kit.
When we get a result in the middle of the range we can feel more confident in what we're seeing.
We can also detect test method errors if we see results significantly higher than the middle, since that shouldn't be possible in a valid test.

Basic idea :
Deliberately create an SN solution whose concentration is in the middle of the test kit range, provided the SN is 100% purity, by dissolving a known amount of SN in a known volume of water.

e.g. If our kit tests up to 10mg/L, then create an SN solution of 5mg/L (assuming 100% SN purity), by placing 5mg of SN into 1 litre of water. If the kit shows around 5mg/L, then the SN must be almost 100% pure.

The numbers used below assume a kit that tests up to 10mg/L.
Modify the numbers based on the range of your test kit.


Equipment :
Kitchen scales that can measure to 0.1g accuracy (or better) for method 1, or to 1g accuracy for method 2
Aquarium test kit that tests up to 10mg/L nitrite.
Two 1 litre bottles of water ("bottles 1 and 2"). Ideally use distilled water, though I assume you could probably use regular mineral water, or maybe even tap water.
Syringe or pipette that can measure 5ml for method 1, or 0.5ml or 1.0ml for method 2
(though if you have a 1ml syringe or pipette then you could use it 5 times when the step requires 5ml to be extracted)

(note : If you don't use distilled water then you may want to separately test some water from the same source, without any SN added, to check the "baseline" level. You should see close to the minimum on the test range. You could still do this if using distilled water, to validate the test kit gives sensible results).

=======================================================================

Method 1 : Requires kitchen scales with 0.1g accuracy (or better)

Weigh out 1.0g of SN and dissolve it in bottle 1.
Put lid back on, shake *very* well.
Bottle 1 now contains 1.0g/L of SN

Use syringe to extract 5ml of liquid from bottle 2.
Squirt liquid away to discard it.
Syringe should now be empty.

Use syringe to extract 5ml of liquid from bottle 1.
The extracted liquid contains 5mg of SN.

Squirt extracted liquid into bottle 2.
Put lid back on, shake bottle 2 *very* well.
Bottle 2 now contains 5mg/L of SN.

Test liquid from bottle 2 using test kit.

If tests show around 5mg/L then the SN was close to 100% purity.
If tests show significantly higher than 5mg/L then the test has been wrongly performed or the test kit is faulty.
If tests show significantly less than 5mg/L then it suggests the SN is of lower purity and may be unsuitable.

Disposal : After testing, further dilute liquids while discarding, e.g. slowly pour liquid into stream of water from tap or from another bottle of water.
This applies particularly to bottle 1 (more concentrated).

After completing the test successfully, you may wish to do another which targets the upper end (maximum) of the test kit to measure the percentage purity of the SN more accurately (if you feel the need). If the values you used for the first test exactly targeted the middle of the test range, then you can simply double the ml amount that is transferred from bottle 1 to bottle 2, eg modify above steps, replacing 5ml (both instances) with 10ml (or you could double the SN amount in g, but that wastes SN for no real benefit).

=======================================================================

Method 2 : If your kitchen scales can only measure to 1g accuracy

This requires a syringe that can measure 0.5ml fairly accurately. If your syringe can measure 1ml accurately, but not 0.5ml, then modify steps, replacing 10g with 5g, and replacing 0.5ml (both instances) with 1ml, although this will be less accurate.

*Be careful* due to higher SN amounts. Ensure disposal steps (see above) followed.

Weigh out 10g of SN and dissolve it in bottle 1.
Put lid back on, shake *very* well.
Bottle 1 now contains 10g/L of SN

Use syringe to extract 0.5ml of liquid from bottle 2.
Squirt liquid away to discard it.
Syringe should now be empty.

Use syringe to extract 0.5ml of liquid from bottle 1.
The extracted liquid contains 5mg of SN.

For remaining steps, see method 1 (squirt extracted liquid into bottle 2, etc).

=======================================================================


ANOTHER EXAMPLE :
Test kit that measures 0.3 to 3.3 mg/L
We will aim to create a solution of 2 mg/L.


Method 1 : Requires kitchen scales with 0.1g accuracy (or better)

Weigh out 1.0g of SN and dissolve it in bottle 1.
Put lid back on, shake *very* well.
Bottle 1 now contains 1.0g/L of SN

Use syringe to extract 2ml of liquid from bottle 2.
Squirt liquid away to discard it.
Syringe should now be empty.

Use syringe to extract 2ml of liquid from bottle 1.
The extracted liquid contains 2mg of SN.

Squirt extracted liquid into bottle 2.
Put lid back on, shake bottle 2 *very* well.
Bottle 2 now contains 2mg/L of SN.

Test liquid from bottle 2 using test kit.

If tests show around 2mg/L then the SN was close to 100% purity.
If tests show significantly higher than 2mg/L then the test has been wrongly performed or the test kit is faulty.
If tests show significantly less than 2mg/L then it suggests the SN is of lower purity and may be unsuitable.

Follow disposal steps (see above)

=======================================================================

Method 2 : If your kitchen scales can only measure to 1g accuracy

This assumes a syringe that can measure 0.5ml fairly accurately. If your syringe can measure 0.25ml accurately, then modify steps, replacing 4g with 8g, and replacing 0.5ml (both instances) with 0.25ml, for better accuracy.

Weigh out 4g of SN and dissolve it in bottle 1.
Put lid back on, shake *very* well.
Bottle 1 now contains 4g/L of SN

Use syringe to extract 0.5ml of liquid from bottle 2.
Squirt liquid away to discard it.
Syringe should now be empty.

Use syringe to extract 0.5ml of liquid from bottle 1.
The extracted liquid contains 2mg of SN.

For remaining steps, see method 1 (squirt extracted liquid into bottle 2, etc).



other useful threads :
https://sanctioned-suicide.net/thre...he-aquarium-testing-strips.31522/#post-589366
https://sanctioned-suicide.net/thre...-an-aquarium-testing-kit-rough-version.18188/

 

[Nottoohotlatte]

Wow, very thorough.

Great job, I'm sure that was a lot of hard work!

 

[jgm63]

SN aquarium purity testing mathematics

fundamental inputs :

v1 : volume of water in ml in bottle 1
v2 : volume of water in ml in bottle 2
w : weight of SN in mg
t : transferred volume of water in ml, from bottle 1 to 2
tc : target concentration in mg/ml

(see first post in this thread to understand what bottle 1 and 2 are, etc)

----------------------------------------------------------------------
derived values :

c1 : concentration of SN in mg/ml in bottle 1
c2 : concentration of SN in mg/ml in bottle 2
tw : transferred weight of SN in mg, from bottle 1 to 2

It should be easy to see that :
c1 = w / v1 [1]
tw = t * c1 [2]
c2 = tw / v2 [3]
----------------------------------------------------------------------
Combining [2] and [3] gives :
c2 = ( t * c1 ) / v2

Including [1] gives :
c2 = ( t * w / v1 ) / v2
c2 = ( t * w ) / ( v1 * v2 ) [4]

tc is the target value for c2, so we can re-state [4], as :
tc = ( t * w ) / ( v1 * v2 )

We can rearrange the above as needed, depending on which items are known, and which we are trying to determine. Doing that yields :
t = ( tc * v1 * v2 ) / w
w = ( tc * v1 * v2 ) / t
v1 = w * t / ( tc * v2 )
v2 = w * t / ( tc * v1 )
tc = w * t / ( v1 * v2 )

Using above equations, 4 things need to be known, and the 5th thing can be determined.
Pick the equation for the thing you want to determine. Example below shows how that works.
-------------------------------------------------------------------------------------------------
Example 1 :
We've decided to use 1 litre of water in bottles 1 and 2, and use 2.0g of SN.
Our test kit can measure up to 10 mg/L
We've decided to "target" the middle of the test range, ie 5mg/L
How much transferred volume of water should I use ?

So our 4 known things are :
v1 = 1000 v2 = 1000 w = 2000 tc = 5 / 1000 = 0.005
(Convert from mg/L to mg/ml, so divide by 1000. Convert volumes to ml, and weight to mg, so those are multiplied by 1000)

t is what we're trying to determine, so use equation for t :
t = ( tc * v1 * v2 ) / w

So :
t = ( 0.005 * 1000 * 1000 ) / 2000 = 2.5 ml

So, we've determined we should transfer 2.5 ml of water from bottle 1 to 2.
If the SN is 100% pure, then this should give a 5 mg/L result on the test kit.
-------------------------------------------------------------------------------------------------
Example 1b) : As example 1), except :
We've decided to "target" the max of the test range, ie 10mg/L
tc = 10 / 1000 = 0.01
and :
t = ( 0.01 * 1000 * 1000 ) / 2000 = 5 ml

So, we would transfer 5 ml of water from bottle 1 to 2.
If the SN is 100% pure, then this should give a 10 mg/L result on the test kit.
-------------------------------------------------------------------------------------------------
Example 2 :
We've decided to use 1 litre of water in bottles 1 and 2, and to transfer 10ml of water
Our test kit can measure up to 10 mg/L
We've decided to "target" the middle of the test range, ie 5mg/L
How much SN should I use ?
v1 = 1000 v2 = 1000 t = 10 tc = 5 / 1000 = 0.005

w = ( tc * v1 * v2 ) / ( 2 * t )

w = ( 0.005 * 1000 * 1000 ) / 10 = 500 mg = 0.5g

If the SN is 100% pure, then we should see 5 mg/L on the test kit.
-------------------------------------------------------------------------------------------------
Example 2b) : As example 2), except :
We've decided to "target" the max of the test range, ie 10mg/L
tc = 10 / 1000 = 0.01
and :
w = ( 0.01 * 1000 * 1000 ) / 10 = 1000 mg = 1.0g

If the SN is 100% pure, then we should see 10 mg/L on the test kit.
-------------------------------------------------------------------------------------------------

For another example, see here :
https://sanctioned-suicide.net/threads/has-my-previously-strong-sn-now-degraded.33471/post-644601

 

[autumnal]

SN aquarium purity testing mathematics
[...]

@jgm63, you should totally make and share a Google Sheets spreadsheet which allows users to enter each variable step-by-step and does all the calculations. It would be a real godsend for all of us who aren't mathematically inclined! Also I think there is a lot of brain fuzz around depression and suicidality, and even those of us who would normally understand basic algebraic equations just fizzle out when we try to follow the workings in our current state.

 

[jgm63]

SN aquarium purity testing mathematics : TLDR version....
( longer version above if want to see how formulae were derived )

v1 : volume of water in ml in bottle 1
v2 : volume of water in ml in bottle 2
w : weight of SN in mg
t : transferred volume of water in ml, from bottle 1 to 2
tc : target concentration in mg/ml

(see first post in this thread to understand what bottle 1 and 2 are, etc)

t = ( tc * v1 * v2 ) / w
w = ( tc * v1 * v2 ) / t
v1 = w * t / ( tc * v2 )
v2 = w * t / ( tc * v1 )
tc = w * t / ( v1 * v2 )

Using above equations, 4 things need to be known, and the 5th thing can be determined.
Pick the equation for the thing you want to determine. Example below shows how that works.

Example :
We've decided to use 1 litre of water in bottles 1 and 2, and use 2.0g of SN.
Our test kit can measure up to 10 mg/L.
We've decided to "target" the *middle* of the test range, ie 5 mg/L (see first post in this thread for why I think that's a good idea)
How much transferred volume of water should I use ?

So our 4 known things are :
v1 = 1000 v2 = 1000 w = 2000 tc = 5 / 1000 = 0.005
(Convert from mg/L to mg/ml, so divide by 1000. Convert volumes to ml, and weight to mg, so those are multiplied by 1000)
t is what we're trying to determine, so use equation for t :
t = ( tc * v1 * v2 ) / w

So :
t = ( 0.005 * 1000 * 1000 ) / 2000 = 2.5 ml

So, we've determined we should transfer 2.5 ml of water from bottle 1 to 2.
If the SN is 100% pure, then this should give a 5 mg/L result on the test kit

If we decided to "target" the max of the test range, ie 10mg/L, then :
tc = 10 / 1000 = 0.01
and :
t = ( 0.01 * 1000 * 1000 ) / 2000 = 5 ml
So, we would transfer 5 ml of water from bottle 1 to 2.
If the SN is 100% pure, then this should give a 10 mg/L result on the test kit.

See earlier post for more examples..... There's also a good example here.

 

[Taraxias]

I have this test that has this range .is this ok to use?

• NO2 0-50 mg / l

 

[jgm63]

I have this test that has this range .is this ok to use?

• NO2 0-50 mg / l

That should be okay.
You can use the formulae here

 

[FluffyDove]

My results. Unsure if suitable for ctb

 

[jgm63]

My results. Unsure if suitable for ctb

What values did you use for the following ?

v1 : volume of water in ml in bottle 1
v2 : volume of water in ml in bottle 2
w : weight of SN in mg
t : transferred volume of water in ml, from bottle 1 to 2
tc : target concentration in mg/ml

 

[FluffyDove]

@Red are you able to answer please?

 

[Taraxias]

I found lots of test kits but they dont write anywhere how many mg/l they can test .how to find this?

That should be okay.
You can use the formulae here

I dont unsterstand amything in this... I am not to good with this chemistry math things. I want some help how to use the test i found that says 0-50 mg/l or how to know what all the other kits i found measure up to..

 

[WhatIsMyLife]

Is demineralized water okay to use? In Australia, I can only find demineralized distilled water as the label says.

 

[autumnal]

Is demineralized water okay to use? In Australia, I can only find demineralized distilled water as the label says.

I'm no expert, but they sound pretty similar in practice.

https://www.westlab.com/blog/2017/11/29/the-difference-between-distilled-and-demineralised-water

 

[Red]

Ppppfffftttt
Ok so with brain fog and painkiller head all that equation shit just slides off n around my brain big time lol
I did the test according to the original instructions, method 1. Scales were to 0.01 accuracy. Test kit measured up to 10mg/L, 5ml oral syringe used.
First bottle:1000ml + 1g or 1000mg SN
Second bottle:1000ml
Amount discarded from 2nd bottle: 5ml
Amount 1bottle to 2bottle: 5ml
Bottle 2 should then have had 5mg/L, however tested and looked to be around 1.5mg/L, as above. Plus a nitrate reading of 2.

 

[FluffyDove]

Ppppfffftttt
Ok so with brain fog and painkiller head all that equation shit just slides off n around my brain big time lol
I did the test according to the original instructions, method 1. Scales were to 0.01 accuracy. Test kit measured up to 10mg/L, 5ml oral syringe used.
First bottle:1000ml + 1g or 1000mg SN
Second bottle:1000ml
Amount discarded from 2nd bottle: 5ml
Amount 1bottle to 2bottle: 5ml
Bottle 2 should then have had 5mg/L, however tested and looked to be around 1.5mg/L, as above. Plus a nitrate reading of 2.

Sorry to keep bugging you lol

 

[Red]

Hey no it's fine hon - I'd like reassurance that I did it right as brain isn't my best friend right now lol

 

[thethatsitboy]

@jgm63 Nitrite test kits that measures in ppm. It is the same as mg/L, right?

 

[DyingMiND]

SN aquarium purity testing mathematics

fundamental inputs :

v1 : volume of water in ml in bottle 1
v2 : volume of water in ml in bottle 2
w : weight of SN in mg
t : transferred volume of water in ml, from bottle 1 to 2
tc : target concentration in mg/ml

(see first post in this thread to understand what bottle 1 and 2 are, etc)

----------------------------------------------------------------------
derived values :

c1 : concentration of SN in mg/ml in bottle 1
c2 : concentration of SN in mg/ml in bottle 2
tw : transferred weight of SN in mg, from bottle 1 to 2

It should be easy to see that :
c1 = w / v1 [1]
tw = t * c1 [2]
c2 = tw / v2 [3]
----------------------------------------------------------------------
Combining [2] and [3] gives :
c2 = ( t * c1 ) / v2

Including [1] gives :
c2 = ( t * w / v1 ) / v2
c2 = ( t * w ) / ( v1 * v2 ) [4]

tc is the target value for c2, so we can re-state [4], as :
tc = ( t * w ) / ( v1 * v2 )

We can rearrange the above as needed, depending on which items are known, and which we are trying to determine. Doing that yields :
t = ( tc * v1 * v2 ) / w
w = ( tc * v1 * v2 ) / t
v1 = w * t / ( tc * v2 )
v2 = w * t / ( tc * v1 )
tc = w * t / ( v1 * v2 )

Using above equations, 4 things need to be known, and the 5th thing can be determined.
Pick the equation for the thing you want to determine. Example below shows how that works.
-------------------------------------------------------------------------------------------------
Example 1 :
We've decided to use 1 litre of water in bottles 1 and 2, and use 2.0g of SN.
Our test kit can measure up to 10 mg/L
We've decided to "target" the middle of the test range, ie 5mg/L
How much transferred volume of water should I use ?

So our 4 known things are :
v1 = 1000 v2 = 1000 w = 2000 tc = 5 / 1000 = 0.005
(Convert from mg/L to mg/ml, so divide by 1000. Convert volumes to ml, and weight to mg, so those are multiplied by 1000)

t is what we're trying to determine, so use equation for t :
t = ( tc * v1 * v2 ) / w

So :
t = ( 0.005 * 1000 * 1000 ) / 2000 = 2.5 ml

So, we've determined we should transfer 2.5 ml of water from bottle 1 to 2.
If the SN is 100% pure, then this should give a 5 mg/L result on the test kit.
-------------------------------------------------------------------------------------------------
Example 1b) : As example 1), except :
We've decided to "target" the max of the test range, ie 10mg/L
tc = 10 / 1000 = 0.01
and :
t = ( 0.01 * 1000 * 1000 ) / 2000 = 5 ml

So, we would transfer 5 ml of water from bottle 1 to 2.
If the SN is 100% pure, then this should give a 10 mg/L result on the test kit.
-------------------------------------------------------------------------------------------------
Example 2 :
We've decided to use 1 litre of water in bottles 1 and 2, and to transfer 10ml of water
Our test kit can measure up to 10 mg/L
We've decided to "target" the middle of the test range, ie 5mg/L
How much SN should I use ?
v1 = 1000 v2 = 1000 t = 10 tc = 5 / 1000 = 0.005

w = ( tc * v1 * v2 ) / ( 2 * t )

w = ( 0.005 * 1000 * 1000 ) / 10 = 500 mg = 0.5g

If the SN is 100% pure, then we should see 5 mg/L on the test kit.
-------------------------------------------------------------------------------------------------
Example 2b) : As example 2), except :
We've decided to "target" the max of the test range, ie 10mg/L
tc = 10 / 1000 = 0.01
and :
w = ( 0.01 * 1000 * 1000 ) / 10 = 1000 mg = 1.0g

If the SN is 100% pure, then we should see 10 mg/L on the test kit.
-------------------------------------------------------------------------------------------------

For another example, see here :
https://sanctioned-suicide.net/threads/has-my-previously-strong-sn-now-degraded.33471/post-644601

I'm having difficulty understanding the units in the equation for w in the 2b example. You get the amount in grams for w. But, how do you get that it should be 10 mg per liter which is the concentration? I understand how the units cancel out but when you write that we should see 10mg/L on the test kit, I don't understand that part.

Could you help me understand?

Thanks

 

[headcase95]

If tests show around 5mg/L then the SN was close to 100% purity.
If tests show significantly higher than 5mg/L then the test has been wrongly performed or the test kit is faulty.
If tests show significantly less than 5mg/L then it suggests the SN is of lower purity and may be unsuitable.

OP is gone, hopefully someone else can answer this for me..

There's another thread on aquarium tests that shows his SN at 10mg/L. Do you think his test is faulty? Why would 5mg/L be better than 10 when 10 is the max and we want as much nitrite as possibe?

My test showed about 7 or 8 grams/L of nitrite, but also showed about 100g/L of nitrate, 2nd result from the max. What do you think that means? is my SN bad or the test?

 

[Zegers]

This sounds too complicated when all you have to do is get a cut and see if the SN goes dark, all this seems overthink it to keep putting it off as the SI wants

 

[diyCTB]

How do you test with 4x 500ml bottles? What to adjust? Water amount to equate 2x of 1L bottles by combining 4x 500ml bottles or SN amount?