Looking to build a poor man doser!

[ALBERTA REEF]

Too build a poor man doser. What I am looking for is Ideas, Pictures, drawings and materials lists. The goal is to build one that is reliable and anyone can put together. Materials has to be easy to get from LFS, Hardware stores, exc.

[mark]

could be as simple as a Aqualift pump and a wall timer (see here) or a DIY dosing pump and again a wall timer (for 2 part ~$150)

[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...

[tlo]

2lt pop bottle with airline tube (small hole drilled in popbottle lid, with a little glue to keep from leaking)
I have the bottle upside down above the tank on a wall hook and a knot in the line to keep it at my desired steady drip.

[fencer]

I am not kidding but I saw Snappy use two plastic beer glasses with holes in them to drip dose. I don't think he uses that method anymore

[StirCrazy]

you have to define pourman's.. you could buy a couple of these and a couplr cheep timers

http://www.aptinstruments.com/Mercha...ory_Code=SP100


Steve

[Delphinus]

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. )

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...

[Snappy]

Originally Posted by fencer

I am not kidding but I saw Snappy use two plastic beer glasses with holes in them to drip dose. I don't think he uses that method anymore

Yes I did that up until about a year ago. It works pretty good.

[banditpowdercoat]

Originally Posted by Snappy

Yes I did that up until about a year ago. It works pretty good.

As long as you didn't forget and fill them up with your beer, and drink the dose!!!

[DiverDude]

Peristaltic pumps are best because they are positive displacement devices. They work by using a 2 rollers to squeeze a section on tubing and force the contents out -much like you get a freezee out of it's package by squeezing your fingers together and sliding them up it's length !

The difference is that in this case, the tubing has 'memory' and opens back up as the roller passes, sucking more fluid in so the process continues.

If you know the cross-section of the tubing and the radial distance between centres of the rollers then you can know *exactly* how much liquid will be dispensed per rotation of the head assembly. The motors on these pumps are run through a planetary gear train to reduce the output shaft speed so it's much easier to control dosing by timing the motor run.

The tubing used is a key element. It must be of a special formulation that retains its' shape after repeated squeezings. Various types are available for dosing different chemicals. The best part is that whatever is being dosed never comes into contact with any part of the pump.