I made a real simple doser for dosing kalkwasser by using a salt container, some plastic airline rod, and a maxijet airflow valve. For those of you not wanting to spend $50-$300 on a dosing pump, this is a great, and surprisingly accurate alterative.
I use oceanic salt so I have plenty of these salt containers lying around. First you drill two holes in the lid. Use a bit that has the same diameter of the airline rod. Take a piece of airline rod and cut it the heigth of the container plus a little bit more for the airline hose. For the second hole, you will cut 2 inches of airline rod. Insert the two rods into the cap and apply a thick layer of epoxy or resin around the rods and the lid. Be sure to scrap the lid real good first so the epoxy will have something to grab hold of. Once is has fully cured, screw it into the container and viola! Connect the short tube to your air pump and connect the long tube to a maxijet airline valve. The maxijet valve works perfectly because you can adjust the drip flow in precise increments.
A couple of things I found while using this setup. Normally, when you mix up kalkwasser, you ear out the clear water on top. The cloudy water on bottom is supersaturated. This ensures that your tank wont precipatate...this is bad. So when you are mixing up the solution of kalkwasser for the jug, you have to make sure the solution isnt super saturated. If you are already using kalkwasser for make up water, then you already know this. Second, make sure you are not stressing your airpump out. If you connect the container up to an airpump at full bore, then the container is either going to pop or the airpump will overheat. I have an exisitng 4 way valve that connects my skimmer, airpump, and doser. This way I can adjust the amount of air that is going to the doser.
DIY Doser
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