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Discussion Starter · #1 ·
This is a very simple project that I developed, Eheim products are horribly expensive in Mexico, It was improved by Ruud and now published (in Dutch) in his pages.
All you need is a timer, syringes, 2 check valves, a "T", small screws, pieces of sheet metal, some spare time.
I didn´t use the aluminum Ruud used as a base for the syringe but instead used a piece of PVC tubing (A Dremel tool help me carved it). A small screw works as a pivot (placed where "Rotate" is) I use a piece of sheet metal instead of that strange beige thing
A check valve in one side allows the fertilizer to go into the syringe, another one allows the fertilizer to go to the aquarium
Terumo syringes work better than BD, I tried all sizes from 60 ml to 1 ml, only 1 and 3 ml worked fine, bigger ones stuck, the injection cycle lasts 12 hours

Here's a photo (from Ruud pages)
 

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Discussion Starter · #3 ·
I tried a bigger timer but to my surprise the electric motor is the same as in the small ones
 

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Discussion Starter · #8 ·
You're right it only fertilizes half of the day, no reprograming is necesary the timer just keep going
As I tried to explain in the original post, I made a sleeve with a piece of PVC pipe, this is where you place the screws and attach the syringe, I forgot my camera today but I'll add some photos tomorrow.
With this kind of timer you can't dose 8 ml, the logical way was to use a 10 ml syringe which I tried (also tried 5, 20, and 60 ml), but is not reliable, it gets stuck frequently due to the lack of power from the small timer motor, if you can find a bigger one (like gpodio suggests it may work), this small timer can work with 1 and 3 ml syringes, they can deliver 0.1 to 0.7 ml (1 ml syringe) and 0.5 to 2.4 ml (3 ml syringe)
You should try with different sizes and brand names, not all of them work, some stuck quite easy (BD), for me Terumo worked, but I don't know if we have the same products
Another idea, if you find a bigger motor, why not 2 opposing syringes? (Like a BMW motorcycle engine) it may work and you have all day dosing, or dosing 2 different fertilizers

As you have already noticed, English is not my mother tongue, so feel free to edit the post, saludos desde Guadalajara
By the way I haven't seen yet an American (U.S.) posting in Spanish, why don't you try ? http://www.drpez.net/panel/showthread.php?t=68288 :D
 

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Discussion Starter · #16 ·
Yes in my own dispenser the pivot point is very close to the tip of the syringe (as I told you before I use PVC pipes to make a sleeve for the syringe, it's easier to work with), today I found a 2 rpm motor,and like plant brain said I just have to add more water to my fert mixture, and diminish the quantity of fertilizer per cycle going into the tank.
All improvements are welcomed (and wanted) so far is a Mexican/Spain/Dutch/US project :shock: , the original project was very crude but it has been really improved =D> , I hope it works for you too :D
 
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