Perhaps you've read in a book or magazine, or maybe somewhere online, that you need to "drip kalk" as your makeup water. Everyone makes it sound so easy that you really don't want to ask how to actually do it. You're wondering if it's expensive, if it is difficult, and if it is dangerous to your tank? The answers, in order, are: no, no, and no. After reading this web page, you'll be confidently dripping kalk like a pro. The benefits of using kalkwasser will not be discussed here as it has been thoroughly covered in many articles by Randy Holmes-Farley (Link 1, 2,).

You'll need only a few tools: a drill, drill bits, scissors, and a hacksaw blade (optional).

You'll also need some supplies, so make your shopping list. The first stop in this shopping spree will be the grocery store, where you'll be buying a container, some pickling lime, and measuring spoons. First, the container needs to be food grade, preferably made of plastic as glass tends to be too heavy, and second, it should have a screw-on plastic cap. Various sizes of bottled water or sports drink containers work well, although a one or two liter glass bottle will be fine. The size of the container selected should depend on the size of the tank and the amount of evaporative loss. Larger tanks will need larger size containers as they evaporate more water and consequently need more top-off water replaced. In my case, all of my tanks are under 10 gallons, so the size containers pictured here worked fine. Or, alternatively, if the aquarium has a lot of evaporation, consider making two containers; one can be settling while the other is operating and dripping kalk. I've found this to be a viable alternative to carrying large containers of kalk and attempting to secure a heavy container above the tank or sump. Next, purchase some pickling lime (not pickling spice), if the store has any in stock. If they don't have any, that's not a problem; a suitable substitute can be found at our next stop. For a more thorough discussion of the various pickling limes available, see this article by Randy Holmes-Farley. Finally, buy your own set of plastic measuring spoons dedicated for this purpose, you don't want to be sharing food preparation measuring spoons and you'll always want the equipment to be availabe. Keep in mind the spoon has to fit in the mouth of the container you've selected. I've found elongated spoons are much more useful than the typical round measuring spoons.

The next stop is the local fish store. If pickling lime wasn't available at the grocery store, buy some kalkwasser powder here. You'll pay more, but at least they have it in stock, and this project is generally so cheap that you can afford to splurge. Additionally, a length of rigid tubing will be needed; I use 3/16" thin-walled tubing. You'll also need flexible tubing. Before buying it, however, be sure it fits over the rigid tube easily but snugly. I've found most fish stores stock flexible vinyl tubing that is just a little bit too small and difficult to work with, so I stop by the local hardware store and buy the tubing there. The final item to pick up from the local fish store is a small package of plastic airline valves.

So now you have your supplies...

…and you're looking at this conglomeration of stuff and wondering what's next...

Grab the drill! The container's cap needs to have two holes drilled in it (see below). In my case, I used a 7/32" drill bit. A bit of advice... before drilling the top, find a scrap piece of plastic and drill a test hole to confirm the flex tubing fits snugly. Once the correct bit size is determined, drill two holes in the cap, making sure they aren't too close to the edge, since the cap needs to be able to screw back onto the bottle.

The manner in which to assemble the dripper depends on the container used and where it's located relative to the tank. For example, the length of the tubing depends on how far the container will be located from the point you've chosen in the aquarium to dose the kalkwasser. In all cases, however, the tube inside the bottle should end about 3/4" above the bottom. There will be some residue that settles out and you don't want to add that to your system as it may contain some undesirable metal residues. I also use rigid tubing on the outside because flex tends to be difficult to work with, and I've been known to accidentally drip a whole container of kalk outside the tank when using only flex tubing.

By now you're probably wondering about three things: 1) do you have to suck on the drip tube to start the siphon, 2) what does kalk taste like, and 3) what's with the second hole in the cap? Quick answers are: no, I've never tasted it, and it's the siphon starter. Cut another piece of flex tubing and insert it about 1/4" into the second hole. Blowing into the second tube pressurizes the container and forces water into the siphon tube. This assumes, of course, that the airline valve is open. The DIY kalk dripper is now ready for use. Congratulations on a successful project!

Now that the kalk dripper is assembled, next comes the not-so-daunting task of using it.

It's important when planning, and prior to building, the kalk dripper, to find a location in the aquarium where it can drip into turbulent water. Placing the drip into turbulent water assures better dispersion throughout the tank. Also make sure it's safely supported; a kalk container falling and spilling its entire contents can be a disastrous event! Plan the size of the container with the assumption that something will fail and the entire contents may drain quickly into the tank. Some potential pitfalls could include such things as the airline valve falling off (unlikely), the container springing a leak (unlikely), or forgetting to turn down the drip rate after starting the siphon (likely).

The general rule of thumb for mixing kalkwasser is one teaspoon of kalk powder per gallon of water. Fill about 1/3 of the container with RO/DI water and add the kalk. Swirl it around until it's in suspension, then add the rest of the water and cap the container. Be careful with this part, as kalk can be an irritant if it gets onto your skin. I usually mix the kalk in the evening and set the container in place without starting a drip. The next morning it takes just a few seconds to start the siphon and set the drip rate. The proper drip rate depends upon your setup and the water volume of your system. For my small tanks, about one drip per second is slow enough not to cause sudden pH fluctuations and still get the kalk in the tank; obviously, larger tanks can handle faster additions of kalk.

There is some minor maintenance involved in dripping kalk. First, you'll discover a sludge accumulating in the bottom of the container; simply pour it out periodically. Eventually, the airline valve and tubing will start to clog with calcium deposits. You'll realize this when the drip rate becomes hard to regulate or stops completely. Either dripping plain RO/DI water through it every couple of weeks or removing the valve and soaking it in vinegar will easily solve this problem.