Recommended Scale for Micros

[FishWorks]

Hey All,

Can anyone recommend a weigh scale that is accurate enough that I can make a reasonably sized micronutrient solution?
Right now, I am using the AWS Gemini-20. It says it reads up to 20g in .001g increments. It also says error should be within +/- 0.005g. Is this scale good enough?

Right now, to get myself within about 0.89% error for dosing Molybdenum, I calculate I need to make a 10L solution. I dose 20mL 3x per week in a 400L aquarium.
This is probably going to expire before I use most of it.

When I apply my milligram scale for Molybdenum, Rotala Calculator says I add 0.560g to the 10L, instead I add 0.565g, this brings me to 0.89% error.
In contrast, If I should add 0.056g to 1L, instead I add 0.061g, this brings me within 8.93% error

 

[Zeus.]

Normal scale and serial dilution, make stock solution, easy way. highly accurate

 

[dw1305]

Hi all,

Normal scale and serial dilution, make stock solution, easy way. highly accurate

I'm a <"serial dilution"> fan as well.

cheers Darrel

 

[X3NiTH]

Yup me too!

These are 100ml bottles, the salt weight per 100ml is on the label. When making up 500ml of Micro I add 1ml from each of these to my receiving water to reach my desired target per dose, again written on the label. The Ionic solutions in these bottles will outlast the bottles! Adjust the dosages to your hearts content.

 

[Zeus.]

Yup me too!

View attachment 172950

These are 100ml bottles, the salt weight per 100ml is on the label. When making up 500ml of Micro I add 1ml from each of these to my receiving water to reach my desired target per dose, again written on the label. The Ionic solutions in these bottles will outlast the bottles! Adjust the dosages to your hearts content.

Sometimes I wish I was more OCD as yours makes my bottles look shamefully incomplete

😆

 

[X3NiTH]

Here’s the mix with dosage instructions.

 

[dw1305]

Hi all,

Here’s the mix with dosage instructions.

You are just showing off now.

my bottles look shamefully incomplete

Same for me, I'm always looking at them and going "is that a 3? or is it a 5?".

cheers Darrel

 

[FishWorks]

Here’s the mix with dosage instructions.

View attachment 172952

X3NiTH,

About my AWS Gemini-20 weigh scale. I should assume its good enough as nobody made any recommendations for a weigh scale?
It says it reads up to 20g in .001g increments. It also says error should be within +/- 0.005g.
I think I am still going to need a reliable scale to make the initial solution for the serial dilution method.

I am currently still looking into the serial dilution method.

Thanks everyone

 

[FishWorks]

I think I understand how to perform serial dilution now.
Just talking about Molybdenum for now to isolate variables.

1) Make Acidified Distilled Water by mixing 0.5g of ascorbic acid per 500mL distilled water.
2) Mix 5.6g Molybdenum Crystals (Na2MoO4.2H20) in 100mL of Acidified Distilled Water to make 100X Molybdenum solution.
3) Take 1mL of 100x Molybdenum Solution, then add to a 999mL of Acidified Distilled Water. This comes to 1000mL of final solution containing 0.056g of Molybdenum. 20mL of this should produce 0.0011PPM in a 400L tank.

The Ionic solutions in these bottles will outlast the bottles!

How long before the 100X stock solution expires?

Thanks Everyone!

 

[dw1305]

Hi all,

I should assume its good enough as nobody made any recommendations for a weigh scale?
It says it reads up to 20g in .001g increments. It also says error should be within +/- 0.005g.
I think I am still going to need a reliable scale to make the initial solution for the serial dilution method.

You can get accurate 3 and 4 place balances, but there are a number of provisos.

• They are <"quite expensive">.
• They need regular recalibrating
• They need to be on a solid surface, and
• Protected from air current etc.

Weighting out larger amounts and using serial dilutions is a no brainer, it takes away the requirement for precision and negates all the possible error factors listed. I work next to a lab., and have access to calibrated pipettes and scientific balances, but I usually just use the standard lab. top pan balances with larger weights

The <"AW Gemini 20"> scales you have, there is nothing at all wrong with them and they will weigh larger amounts pretty accurately.

cheers Darrel

 

[dw1305]

Hi all,

How long before the 100X stock solution expires?

If they are sealed (to avoid evaporation) and nothing precipitates out, all of eternity.

cheers Darrel

 

[X3NiTH]

I never acidified the RO/DI I used for the Ionic concentrate since they were single compound solutions used in amounts well below their maximum solubility in water and thus nothing else to form compounds with other than itself so the worst case possible for these solutions over a human lifetime (discounting storage vessel substrate elements) is dehydration and recrystallisation from being kept in an insecure container.