DIY Alkalinity Monitor

[Borat]

Hello US&A fellow reefers.. In this thread I am going to show you super-advanced Kazakh technologies.

I am going to rebuild my DIY Alkalinity Monitor (that is already fully functional for over a year) - except this time I am going to make it as small as possible. The footprint of this device is going to be a mere 105mm x 100mm x 290mm, roughly the size of box used to store expensive wisky...

 

[Borat]

This is what I have already done in the last couple of hours..

Cutting technique is very simple: I use 2x A4 sheets (I use 3mm white Perspex) and cut each in the middle to produce 2 long strips 290mm long and 105mm wide..



I then choose the piece that will be the face of the doser and drill/cut all the required cut-outs (which are otherwise difficult to make once the box is glued)..

 

[Borat]

Pieces are then glued with Tensol 12

 

[Borat]

I am going to use Chinese dosing heads, they are roughlt $10 each as ordered from China..

I glue 2 additional strips of acrylic about 40mm wide to the top and bottom parts:
- the enclosure will have 3 removable covers: top, bottom and back
- each removable cover will held by screws, therefore these 2 strips of acrylic are there to hold nut for such screws
- the placement is shiftted away from motors towards the back, this is done intentionally to allow for easy access to the reaction chamber that will sit next to motor close to the doser front part.. you shall see that soon!

 

[Borat]

There will be a small OLED screen and a rotary encoder. The doser will be wi-fi enabled and will send all results/notifications via email as most of my devices do..

In terms of PH board - I will take it from my existing (my larger in size) alk monitor, it will be DF ROBOT SEN016 v 1.2 board. 12v power will be supplied externally via 5.5mm DC connector..

 

[Borat]

I bought an off-cut tube of acrylic for reaction chamber cheaply (700mm length only cost me about $5 US&A bucks!):

this is 36mm ID / 40mm OD

 

[Borat]

This miniature 12v fan will serve as stirrer, I could not find PWM controlled mini-fans, all of fans of this size only have 2 wires (even TACH wire is not present here). Therefore speed control will be achieved by varying the input voltage.

I already have a board in spares that converts 12v + PWM signal into 0v - 10v analogue output.. I am going to show the picture of this board later..

 

[Montiman]

Liking where this is going.

 

[iLMaRiO]

with such a small reaction chamber, how much precision would you get ? a single drop of reagent would make huge changes in ph

 

[Borat]

with such a small reaction chamber, how much precision would you get ? a single drop of reagent would make huge changes in ph

This is a well-tested technology for me now..

Reaction chamber will be 150mm high - this is sufficient to hold 130ml of sample water. The monitor will generally use 100ml sample water. For 100ml sample and alkalinity of 8 DKH the approximate volume of 0.1N hydrochloric acid is 2.9ml. Pumps are able to dose acid with high precision: pumps imperfection will be less than 0.1DKH accuracy.

Main inaccuracy in titration is actually coming from your PH probe precision, not the pumps.

 

[iLMaRiO]

which ph probe will you use ? I'm doing the same tester but with a little bit more water. If i can lower it, i'll be very happy

 

[iLMaRiO]

0.1N not 0.02N like the khkeeper from reef factory or other kh testers ?

 

[Borat]

which ph probe will you use ? I'm doing the same tester but with a little bit more water. If i can lower it, i'll be very happy

I am using Extech Instruments 601500 PH probes throughout my systems: I currently deploy 4 such PH probes, 2 to measure calcium reactor effluent (primary and secondary chambers), 1 to measure tank PH and 1 in existing Alk monitor. These probes are of high quality - and yet they are still quite affordable.

 

[Borat]

0.1N not 0.02N like the khkeeper from reef factory or other kh testers ?

0.1N it is.. I already used about 5L of this reagent over the last year or so..

 

[Borat]

I have a large assortment of strong magnets of different sizes - from prior projects... I will start with the small magnets for now as the stirrer does not need to be very powerfuk..

 

[iLMaRiO]

I am using Extech Instruments 601500 PH probes throughout my systems: I currently deploy 4 such PH probes, 2 to measure calcium reactor effluent (primary and secondary chambers), 1 to measure tank PH and 1 in existing Alk monitor. These probes are of high quality - and yet they are still quite affordable.

connected to which ph board ?

 

[Borat]

You may have missed this post:

There will be a small OLED screen and a rotary encoder. The doser will be wi-fi enabled and will send all results/notifications via email as most of my devices do..

In terms of PH board - I will take it from my existing (my larger in size) alk monitor, it will be DF ROBOT SEN016 v 1.2 board. 12v power will be supplied externally via 5.5mm DC connector..

 

[iLMaRiO]

You may have missed this post:

same board used here

 

[Borat]

The stirrer/reagent chamber assembly is the most delicate part. Seemingly it is simply a tube above the fan with magnets attached, but there are some aspects you really need to think carefully:
- your stirrer assembly needs to be interchangeable, the fan may break one day or you may find the reaction chamber to be inadequate - in which case you would want to be able to only replace the reaction chamber
- when you mount pieces to your main enclosure, you need to carfefully think if you may be obstructing some parts, for example you may find out that you are not able to remove the stepper motor (which may also break one day and require replacement)
- finally when you design components, think about whether you will be able to tighten the screws: you may not be able to tighten the screws that are too close to the enclosure wall or are obstructed by other parts

All these considerations need to be thought through and only once everything is analysed and measured / tried - should you glue components to your main enclosure

I am almost there with the reaction chamber, due to small size of components I had to come up with brand new ideas of how to mount this one and it is very different to how my previous reaction assembly was built (pictures to follow shortly)..

 

[Borat]

I use one of the airline acrylic connectors as the drain connector, I file it flat as far as possible - to make it be as close to the chamber floor as possible.