[CardBoardBoxProcessor]

I dunno if you know what it is but it is basically a small air pump that pumps water and air. it is for salt water tanks to keep their overflow box siphon working.

Could i use one of these for an auto doser?

 

[hooha]

I know someone who uses it for dosing. If you look on one of Wasserpest's DiY dosing threads I think he tried it as well.

2 things are problems with it, if I recall correctly:

The head pressure drops greatly, meaning you only have a certain amount of depth you can place the pump before it doesn't have enough power to overcome gravity.

Also it's hard to get an accurate measurement of how much will go into the tank. If you change the depth of the pump below the water line, the amount pumped in 1 minute (I'd assume you would use an electronic timer if you would try this) changes. Apparently it can also be a big volume as well, which is more difficult to do. The person I know who does this uses the airline regulators to adjust the flow of water, it took him a while to get the amount of ferts he wanted to be added in 1 minute.

 

[whitepine]

I have this on one of my tanks. I too have it set up with a airline regulator. I set up the pump exactly where I wanted it. I then filled up the container with water and ran it for for a few minutes, I then timed it for 2 minutes with a container to catch the water. Measured this amount and set up my ferts to what came out in 2 minutes. I have it below my tank and it doesn't have a ton of head. Make sure that the bottle is below the tank though.

Cheers, Whitepine

 

[vidiots]

I have this on one of my tanks. I too have it set up with a airline regulator. I set up the pump exactly where I wanted it. I then filled up the container with water and ran it for for a few minutes, I then timed it for 2 minutes with a container to catch the water. Measured this amount and set up my ferts to what came out in 2 minutes. I have it below my tank and it doesn't have a ton of head. Make sure that the bottle is below the tank though.
Cheers, Whitepine

I am also using the TOM Aqua Lifter AW-20 vacuum pump as my auto doser. I've been using it for several months now with no problems. I have the pump sitting on top of my sump tank, using gallon milk jugs as my fert reservior which are sitting on the floor next to my sump tank. There is a short piece of tubing that goes from the pumps output thru the sump tank lid but well above the water level so there is no need for a check valve to prevent syphon. The ferts just drip into the tank. At 2min per day with the height I have my pump at it takes about 13 days for the reservoir empty. I put 14 days worth of ferts in and allow it to slighly overdose 13days and run dry the 14th, then refill. (1/13th of a dose overdosed isn't that much)

Between the autodoser and my automatic water changer the fert levels are fairly constant in my tank the only variables are the fish and plant load which change slowly overtime. This means that I only have to make minor adjustments to my doses every couple of months to keep things constant.