# DIY auto dosing system



## Treasure chest

Over the last few weeks, I managed to build an auto doser. It is for dosing nutrients into my planted tank. I have tried different method of auto dosing before including using timer based air pump injection system as well as aqua lifter pump direct injection. However, every single method I have tried was not very reliable. They were difficult to adjust, hard to control out put also dosage varied when liquid level changed. Finally, I decided to make a real auto doser. I ordered some peristaltic pumps; PWM controllers from ebay. Using some existing scrap material and spare parts, I put together a 3 heads auto doser. The doser is based on timer and motor controller to adjust the out put. At first, I was going to use an Arduino micro controller but ended up just using timer and PWM for simplicity. Arduino is an excellent option to do this kind of job, I have built laser camera trigger, parachute deploy mechanism for my water bottle rocket and some other stuff using Arduino controller with great precision results. However, I probably need more parts and effort to put everything into a decent package if I go with Arduino route for the doser. Timer and motor controller is more likely to be more reliable and easier to maintain. The on board timer is a solid state delay timer, I use this to create finer resolution of adjustment from 1 minute increment provided by regular house hold timer. Today, I have added final touch to the system and briefly ran some test. It was a success. the out put is easy to adjust and consistent. I would like to share this with everyone who is interested. It is a fun project.

Motors and PWM controller top side









PWM controllers on bottom side









Front









Back


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## effox

Very cool!


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## shift

Nice job Treasure, it looks good!


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## gklaw

Wow. zooooo, way above my head. I would call this a YDIFM "You Do It For Me" haha.

Impressive !!


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## Treasure chest

Thanks everyone for your kind words. Along with building the dosing head unit, I also built a magnetic stirrer storage system. I know it is probably over kill for planted tank dosing, but hey, it is fun to make and fun to watch when it goes into action. The stirrer is designed to be connect to the doser head unit, controlled by the on board timer delay relay. The solid state timer delay relay is a DPDT switch. The stirrer is hooked to the always on terminal. When the main timer is switched on, the stirrer goes into action right away, after the set time on the rely is reached, the doser kicks in and therefore cuts off the power of the stirrer, it's like one stone 2 birds Here are some pictures and video to share.

Stirrer









Stirrer with storage container









Stirrer in action









Video


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## shift

Thats awesome! another simple solution could be wire up one of those battery powered drink stir/stick motors in the canister... Looks nice. you did a good job


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## Treasure chest

Shift, the handheld milk frother is a good alternative. I actually considered direct drive method before I started the project, the reason i choose magnetic system is because I wanted to build an air tight system governed by check valves and it would be difficult to have a tight seal if I had to mount the motor on top of the lid. However, I discovered the container I bought from $2 store is not so air tight after all, other better glass containers are available but I am also constrained by the size of my cabinet and volume of the bottle which I need to balance. Plus I didn't want to spend that kind of money just for experimenting. After i briefly ran the test, I figure check valve probably is not needed as rollers in the pump head compress the tube pretty tight already. So if any folks decide to build stirrer, drink stirrer is a good option.


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## Treasure chest

Just upgraded my pump tubes to lab quality compression tubes. Looks and feels really good, A big step up from hobby pumps towards higher quality pumps.


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## monkE

this is a fantastic build man, wish i had one of these when i had my big planted tank going! well done man, keep the updates coming as you put this thing into use!


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## shift

Where did you get those tubes?
I used airline (which is bigger) and slid them overtop of the stock pump tube


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## Treasure chest

Thanks monkE!
Shift, I bought the tube from ebay. The one I bought is made of santoprene. I use black silicone airline tubes feeding solution into the tank. the compression tube is more critical because it is under lot of stress whenever motor is running.


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## Treasure chest

Also added chemical resistant check valves on the output side for fail safe operation, because I plan to submerge feeding tubes below waterline for preventing solution from drying out and clogging the tubes.


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## shift

Are the check vales from e bay as well? I submerged the output of my tubes and only notices a very minimal amount of water in the end of the tube (one of the mixes is darker and you can see the line). Still as a fail safe it's not a bad idea. Are they made to fit the thinner tubing?


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## Treasure chest

Yes ebay. There are couple of scenarios that might cause disaster I can think of. When you submerge the output tube under waterline, if pump roller failed to press shut the tube, it may cause back siphon that drain large amount of water depending how deep your tube go below. Also after a period of time, your compression tube may fail or worse crack, The water will be back siphoned when air is able to enter no longer closed loop. It's better to be safe then sorry to put check valves after the compression tubes. BTW, you can order different size check valve to fit your need.


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## Treasure chest




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## Tommy72a

Oh man.. Who are you? You obviously have some kind of electrical engineer background? Im very impressed! I wondering if your unit has some kind Of dosing adjustment function to calibrate? By the way, how sophisticated is your timer system?


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## Treasure chest

The unit can be adjusted by timer and motor speed controller. My digital house hold timer has a resolution of 1 minute increment. However, the on board timer delay relay has a theoretical resolution of 6 seconds increment, so a combination of both timers enable me to set dosing time to as little as 6 seconds. Dosage is also adjusted by motor speed controller (adjusted by potentiometer dial). Plus I can play with concentration ratio of my solution to achieve desired dosage as well.


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## shift

Looking good Treasure Chest!

Any chance you have a link to the tubes/check valves you went for or atleast what size they are? Looks like we are using the same motors.

I got mine completed and running!


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## Treasure chest

I could not find the same tube for sale anymore, but here is the original link, SANTOPRENE TUBING 2.29mm ID x 0.8mm Wall 15Mtr Reel | eBay Check valve here: Pack of Four (4) 3/16" Viton/Kynar Standard Check Valves Universal | eBay


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## shift

Thank you sir


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## Treasure chest

System test run


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## Treasure chest

My calibration/testing set up. The output is raised to the same height as tank rim edge in order to achieve the same pressure head.


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## shift

Looking good! I like the attention to details. I found that 1s (1000ms) was about 1ml on average on my pumps. One of the 3 took an extra second so they are not all 100% the same


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## Treasure chest

Lack of precision may be a draw back of hobby type pump. I think the better ones use gear motor with bigger compression tubes to achieve more precise output. Ours may be not as precise but should be good enough for hobby use. The dosing volume was an estimated number in the first place so I think it should not be a big deal if it is off a few Mls. We can also minimized deviation by prolonging dosing time with more diluted solutions.


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## shift

Well it's easy enough to just test an measure the result. Atleast for systems that are set it and forget it (especially at $200 cheaper! Than buying one)


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## Treasure chest

Just a quick update, the system is running for almost a month, everything is running consistently. I have a quarter of each mixing left that probably will last me another week. My plants responded very positively for daily dose of nutrients. I can tell they grow healthier than before. Here are couple of pictures to share.
My dosing system installation.









My tank today.


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## Tommy72a

Shift, Treasure Chest, your postings inspired me to purchase an Arduino starter kit. I'm currently spending sometime each night learning how to code. I have zero experience so it's been a slow start but excited about the limitless potential.

I have to ask, looking back on this project do you wish you had included a LCD display on your project? Do you think the lab grade motor was worth the upgrade? Do you care to share the coding? Lastly do you think auto mixer was worth the build? Nice build by the way. 
Thanks!


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## Treasure chest

Arduino is fun, I am sure you will enjoy as you learn. IMHO, adding LCD could make the project more complicated. Standard Arduino board has limited pins and LCD board uses quite a few of them then leave you less to play with. I am happy with my hobby grade pump with tube upgrade. They've been working flawlessly for the last half a year. Depending on what are you planning to dose and concentration of the mixture, auto stirrer may help on consistent output. Of course if you dilute the mixture a lot and filter out the impurity you should be fine without one.


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## kacairns

Tommy72a said:


> Shift, Treasure Chest, your postings inspired me to purchase an Arduino starter kit. I'm currently spending sometime each night learning how to code. I have zero experience so it's been a slow start but excited about the limitless potential.
> 
> I have to ask, looking back on this project do you wish you had included a LCD display on your project? Do you think the lab grade motor was worth the upgrade? Do you care to share the coding? Lastly do you think auto mixer was worth the build? Nice build by the way.
> Thanks!





Treasure chest said:


> Arduino is fun, I am sure you will enjoy as you learn. IMHO, adding LCD could make the project more complicated. Standard Arduino board has limited pins and LCD board uses quite a few of them then leave you less to play with. I am happy with my hobby grade pump with tube upgrade. They've been working flawlessly for the last half a year. Depending on what are you planning to dose and concentration of the mixture, auto stirrer may help on consistent output. Of course if you dilute the mixture a lot and filter out the impurity you should be fine without one.


I build mine based off shifts setup and included my code on my 180g planted tank thread if you want more code to look at for arduino. Building mine without the hand auto stir I can tell you, that having the auto-stir is a good idea otherwise depending on what you're dosing, you'll be shaking your containers often to remix or get the particles that haven't broken down back up into the body of water so they can be sucked out and into the tank to properly break down.

LCD is nice, but as treasure says, doesn't leave you with much unless you go with bigger boards and more complicated setup, then you're starting to get to the money point of it being same price to go out and buy a doser instead of building one yourself. I did wish though I had option at times while testing for a display so I could see what time it was in the count and so on


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## wish

Oh my goodness, that looks amazing. Great work.


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## Florios

where did you get the mixers? and jars?


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## Treasure chest

The stir bars were bought from eBay while the jars were bought from dollar store

Sent from my Nexus 4 using Tapatalk


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