Automatic Test Cuvette Shaker

[Mas0n]

Been working on a fun little project the past week! I made a DIY automatic shaker for my Hanna cuvettes.


The problem:

The vigorous 120s of shaking for the NO3 test, and the gentler 120s for the PO4 test, were getting annoying with how often I'm testing right now.

Repeatability was bugging me too. I was getting inconsistent NO3 and PO4 results, probably from being lazy and not setting a timer or not shaking hard enough. Just seems like doing it by hand leaves a lot of room for variation. And PO4 will read high if air bubbles get in the sample from shaking too hard.


The solution:

Super simple operation, two buttons. One for PO4 and one for NO3. It shakes the cuvette for 120s, then stops and beeps.

PO4 mode does 180 degree inversions with a delay in between so the sample can mix like the instructions say. NO3 mode is constant and vigorous.

 

[Jay Hemdal Verified Community Expert]

Been working on a fun little project the past week! I made a DIY automatic shaker for my Hanna cuvettes.


The problem:

The vigorous 120s of shaking for the NO3 test, and the gentler 120s for the PO4 test, were getting annoying with how often I'm testing right now.

Repeatability was bugging me too. I was getting inconsistent NO3 and PO4 results, probably from being lazy and not setting a timer or not shaking hard enough. Just seems like doing it by hand leaves a lot of room for variation. And PO4 will read high if air bubbles get in the sample from shaking too hard.


The solution:

Super simple operation, two buttons. One for PO4 and one for NO3. It shakes the cuvette for 120s, then stops and beeps.

PO4 mode does 180 degree inversions with a delay in between so the sample can mix like the instructions say. NO3 mode is constant and vigorous.

Very cool! I've had issues with reproducibility in Hach nitrate tests due to inconsistent shaking on my part. Even if the shaking this machine produces isn't 100% equivalent to how the "human shaking" should be performed, it would still be more consistent, allowing you to more easily compare test results.

Here is another version from a few years ago:
https://www.reef2reef.com/threads/hanna-checker-cuvette-mixer.763431/

 

[Acro Junky]

I mean I tested daily for a few months straight never skipped a beat. Throw a little YouTube on and sometimes you forget you are shaking haha!

 

[CrewePD210]

What is that?

 

[Privateye]

Very cool! I've had issues with reproducibility in Hach nitrate tests due to inconsistent shaking on my part. Even if the shaking this machine produces isn't 100% equivalent to how the "human shaking" should be performed, it would still be more consistent, allowing you to more easily compare test results.

Here is another version from a few years ago:
https://www.reef2reef.com/threads/hanna-checker-cuvette-mixer.763431/

Those Hach nitrate tests can be a major pain! And they're extremely inaccurate in saltwater, which makes shaking play an even larger role. The chloride coats the cadmium, preventing interaction.

 

[Jay Hemdal Verified Community Expert]

Those Hach nitrate tests can be a major pain! And they're extremely inaccurate in saltwater, which makes shaking play an even larger role. The chloride coats the cadmium, preventing interaction.

I stopped using that test about 15 years ago - the cadmium dust, even with a fume hood, scared me too much.

 

[exnisstech]

Cool diy but way to noisy for me. I'm sure my dogs would find it interesting lol. I use a smart stir that I picked up on clearance for $5
PS. Those don't look like Hanna cuvettes and lids?

 

[BeanAnimal]

Nice work. I would certainly consider put a silent step driver in there, that would drive me bonkers.

 

[Mas0n]

Cool diy but way to noisy for me. I'm sure my dogs would find it interesting lol. I use a smart stir that I picked up on clearance for $5
PS. Those don't look like Hanna cuvettes and lids?

Ha! Definitely noisy, I’m going to look into a different motor once this cheap plastic gear servo bites the dust.

The cuvettes belong to the Hanna Marine Master test kit. HI731360

Wish it utilized the standard and cheaper Hanna cuvettes.

 

[Mas0n]

Nice work. I would certainly consider put a silent step driver in there, that would drive me bonkers.

I thought about that initially and still want to experiment with a stepper motor!

I went with the servo due to speed and simplicity, everything also runs nicely on 5v. I believe I would need 12v to properly drive a stepper.

Thoughts? This is my first “electronics” project, so I’m just stepping (ha) into this world.

 

[Dr4gula.f32]

there is a mag stirrer on amazon specifially made for our cuvettes its less than 20 bucks. rechargable

 

[Mas0n]

there is a mag stirrer on amazon specifially made for our cuvettes its less than 20 bucks. rechargable

I’ve seen those, not interested in dealing with removing and cleaning the little pill between tests. I am looking for maximum laziness

 

[exnisstech]

I’ve seen those, not interested in dealing with removing and cleaning the little pill between tests. I am looking for maximum laziness

Call me reckless but I've never cleaned a stir bar. Just wipe it with a paper towel and back in the container. Hasn't been a problem that I'm aware of in the years I've been using them