dosing pump for fish tank

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TungstenE2
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Posts: 87
Joined: 03 Apr 2018, 21:46

dosing pump for fish tank

#1 Post by TungstenE2 » 07 Nov 2019, 14:20

Hi all,

I have seen some post during the last years on different solutions on dosing pumps, but none of them with all details or final status.

I would like to build a dosing pump for my fish tank in order to have fertilizer adding automated using Wemos D1 mini and ESPeasy. Dosing should be about 4ml a day and 2-3 pumps.

So my current open questions are at the moment:

- which motor shield to be used supported by ESPeasy already?
Adafruit, Wemos V1 or V2 ( have working Wemos V1 motorshield for the chicken house)

- which motor to be used?
stepper or normal DC
3V or 6V

- which peristaltic pump to be used?
self sucking
no reverse flowing of liquids

So is there anybody out there who did this already or can share some thoughts on this?

thx

Shardan
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Posts: 1122
Joined: 03 Sep 2016, 23:27
Location: Bielefeld / Germany

Re: dosing pump for fish tank

#2 Post by Shardan » 08 Nov 2019, 14:30

Hello TungstenE2,

well, I didn't with ESPeasy, but I've developed such pumps for my former company
(we developed fish tanks, pH control, light, heating, analytics etc...) some years ago
so I can give you some hints that might be usefull.

The type of the pump: Using a stepper isn't really necessary, a DC type will do.
Why? For sure a stepper can do dosing very exact. But your fish tank differs in what is needed.
More daylight or less, some more feeding fish, some less... all this has some influence on how
much fertilizer the plants need. A super exact dosing with stepper is nice. As long as we are not able
to use sensors for fertilizer (dissolved iron for example) this makes no sense.

Second: At least some fertilizers tend to crystalize over time in the pump and the tubes.
This gives several problems from damaged tubes to water flowing back.
We used a bigger tank for fertilizer, a 0,5l or 1l bottle and thinned the fertilizer with
distilled water. Then dosage was raised accordingly.

Third: Use a "non-return valve".
I've seen some peristaltic pumps allowing a flow back of water from the tank after some usage time.
Slightly damaged tubes, some particles in the liquid.... some more causes for this.
Use a valve with spring so it securely closes.

I'd use a DC motor and do dosage just per time. More fertilizer = run motor 7 seconds instead of 5 secs twice a day.
Or more fertilizer = run motor for 5 secs, but 3 times instead of 2 times per day.

For this case a motor shield isn't necessary. A power FET or relay will do the job making circuits more simple.
Regards
Shardan

TungstenE2
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Posts: 87
Joined: 03 Apr 2018, 21:46

Re: dosing pump for fish tank

#3 Post by TungstenE2 » 09 Nov 2019, 12:57

Hi Shardan,

thx for sharing your thoughs.

Currently I would plan to buy the following:

Motorshield:
https://de.aliexpress.com/item/32898563025.html

Wemos D1:
https://de.aliexpress.com/item/32758176555.html

Also, the motorshield powers the Wemos D1. This means that you only have to power the motor shield with 12V DC.

pending descicions:

- power supply
- spring valve
https://de.aliexpress.com/item/32963864348.htm
- persitaltic pump 12v
https://de.aliexpress.com/item/32821900518.html

Further ideas to share?

thx

Shardan
Normal user
Posts: 1122
Joined: 03 Sep 2016, 23:27
Location: Bielefeld / Germany

Re: dosing pump for fish tank

#4 Post by Shardan » 10 Nov 2019, 19:03

Hello again,

can't say anything about that Wemos board, it is definitely not the classical D1 but an Arduino like version.

I don't know if the motor shield works backpacked to this board.
The shield was made with Arduino Uno or similar in mind - these have 5V GPIO.
The Ali offer just says it can be programmed using Arduino IDE, it says nothing about
compatibility of the GPIOs. As the motor shield uses a PCA9685 it needs a I2C-connection to
the CPU - If the PCA9685 runs on 5V this will not work with the 3.3V ESP8266.
More exact this may lead to damages.

Even if it fits mechanically this doesn't say anything about voltage compatibility.

Spring Valve is worth a try. Some fertilizers might corode the spring
depending on the spring material and fertilizer ingredients. Needs some testing over time.

The pump seems OK to me.
Regards
Shardan

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