This would work but watch out for the windsheild washer pumps. I tried using one for a mister pump on a terrarium once, the pump was nice and cheap but it turned out that despite it being a 12V DC pump, it needed close to 1500mA which is well beyond most simple wall wart power supplies capacities. The worst part was that the amperage wasn't posted on the pump so I had to find the right power supply by trial and error. If the power supply stopped working (ie. burned out) I'd step it up to the next size. Didn't end up being a very cheap DIY project at all.
Also the volume they dispense is sorta high for dosing. You need to be able to control the volume precisely, so slow flows are better to work with.
I still maintain that the best "poor man's auto doser" is to use Aqualifter pumps (anywhere from $10-20 depending on where you shop), a dripline needle valve ($2 maybe at Home Depot) and a timer. Autodosing two part solutions is then done, fairly reliably, for less then $50-60. I don't think it can be done, reliably, for a lot less. The problem is the trial and error in getting the right dose-on times, and dripline settings, to be consistently dosing the same amount day after day, week after week. The problem with 2 part liquids is they tend to have a lot of particulate so you can't close the needlevalve too much or else it will be prone to clogging. That's why a slow peristaltic pump is still better in the end, no restriction needed on the output line, thus no clogging. But peri pumps cost anywhere from $60-100 each so it gets a little outside of the "poor man's auto dosing" category and more into the "middle class auto dosing." (Where "upper class" uses off the shelf dosers in this example.
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Originally Posted by sleschwin
Was wondering about using an windshield washer res kit from princess auto..They hold quite a bit,have a small 12vpump mounted on the bottom add a small timer...  |