To run kalkwasser or not?

I have been running kalkwasser on my 75 gallon since January. Im not sure if it is worth it or not. Anyone running it or has any input on running it or not. Im debating this because when I set up my new 135 (thanks to nikecivic) I either want to run it or don't run it from the start. Im using BW Kalk+2. I little more expensive than the other ones so if I do run Kalk I wont use it on my new tank. Maybe use BRS kalk or something. Any advice?

I only used 2 part so I can't comment on Kalkwasser but its worked for other reefers. Dwolson2 was using it before.

I used to run it on a 75 gallon mixed coral tank but that was a decade ago. The European Reefers, mainly the Germans, run it on all their SPS tanks and have been doing so for 20 years. It's the cheapest way to maintain calcium and alkalinity. However, I'll say that it's easy to overdose and it will simply precipitate to the bottom of your tank. Here's a good thread that has been floating around for years:

When kalkwasser is dosed or dripped into the tank, the following procedure is more or less used. One to three teaspoons of kalkwasser are added to a gallon of water that is to be used for makeup water. The kalkwasser is then gently mixed to saturate the water with the kalkwasser. I say gently, because an important consideration in using kalkwasser is to minimize the amount of air that enters the water during mixing. When kalkwasser is combined with highly aerated water, it forms calcium carbonate, which is not useful in the aquarium. After the gentle mixing, the kalkwasser mix should then sit for a period of a few hours to allow settling of any calcium carbonate that has formed. This, along with some unmixed kalkwasser, will form sediment on the bottom of the container. After settling, the saturated kalkwasser (the liquid above the sediment) is siphoned off to be used for dosing. (More on dosing in a minute.) When using this method of kalkwasser addition, it is important to use the mixed kalkwasser within a few days. Old kalkwasser mix will lose its concentration of calcium in solution, which results in little calcium addition to the aquarium. And it is important to not dose the sediment, which is a mixture of calcium carbonate and calcium hydroxide. Dosing this can result in calcium precipitation, excessive elevation of pH, and decline of alkalinity.

The other method, and generally more preferable method of mixing and dosing kalkwasser, is through the use of a kalkreactor. These devices may go under the name of a calcium reactor, kalkreactor, and Nilsen reactor, to name a few. In fact, there is another type of reactor (to be discussed later) that is also called a calcium reactor that is quite a different device. For the sake of this discussion, I will use the term "kalkreactor". A diagram of this device may be found in Sprung and Delbeek's "The Reef Aquarium, Vol. I", pg. 245. There are also a number of do-it-yourself (DIY) projects on the Internet for building one of these. Essentially, a supply of kalkwasser is inserted into a sealed reactor chamber. Within the chamber is a magnetic stirrer/spinner. Using a dosing pump, water is drawn from a fresh water reservoir and pumped into the reactor chamber, where the magnetic stirrer periodically mixes the water and kalkwasser. The pressure build-up from the dosing pump within the reactor forces the saturated and milky kalkwasser then to be dosed into the aquarium. The advantage of this method is that the calcium concentration of the kalkwasser remains higher, and the mixing procedure requires far less attention.

The procedure for dosing kalkwasser is important. A saturated kalkwasser mix will have a pH that can exceed 12. If added too quickly, the aquarium pH can rise significantly, which stresses the tank inhabitants. Beyond this, a significant pH spike (usually above 8.5 - 8.7) can cause a calcium/carbonate/magnesium precipitation. This leaves the tank with stressed livestock and often less calcium than before dosing. Ideally, a pH monitor and/or controller should be used when dosing kalkwasser to insure that tank pH remains below 8.5, however this is not a requirement. If dosing kalkwasser without a pH monitor, it is important to drip it slowly (around 1 drop/second maximum) into a water stream in a sump or in the tank itself.

The disadvantages of kalkwasser may be fairly apparent. If mixing it for makeup water, it can take time and diligence to mix it properly, and dose it properly. A kalkreactor greatly reduces the inconvenience, and can provide a highly saturated kalkwasser mix.

The advantages of using kalkwasser are many. First, kalkwasser, when mixed properly, is highly saturated in calcium, and leaves no other residues in the aquarium. This accomplishes the primary goal of kalkwasser use, namely increasing calcium availability to aquarium inhabitants. Kalkwasser helps to maintain alkalinity in the aquarium. On this point, I want to highlight that kalkwasser does not increase alkalinity, but rather helps maintain alkalinity by neutralizing acids that would usually be neutralized by resident buffering agents. The result is that carbonates in the aquarium, and thus alkalinity, is preserved. Kalkwasser helps maintain pH. This occurs not only due to the preservation of alkalinity, but also because of the high pH of kalkwasser. When properly dosed, kalkwasser can be used as a tool to gently increase pH to more desirable levels in the aquarium. This is useful in combating the natural trend in closed systems of pH decline. Finally, kalkwasser is known to precipitate phosphates out of solution. What this means is that when calcium hydroxide enters the water, it causes phosphates to fall out of solution. This is helpful in preventing/removing problem causing algae and cynobacteria blooms.

I liked it and have been thinking about running it on my next tank. If you decide to run it, Do not run it through your ATO like many people suggest. Its easier yes, but the chances of OD'ing is higher too.

I have been using kalkwasser for at least a dozen years now in my ATO. I also mix in 80ml of vinegar when mixing it to 'super charge' it. I use an aqualifter for my ATO so it is a slow drip so I don't spike the system every time the ATO kicks on. In the beginning I did have to test a lot to make sure I wasn't ODing the tank. I still have over 50% of the gallon container of BRS Kalk that I bought 8+ years ago, the stuff lasts forever it seems. It is by far the cheapest and easiest way to maintain alk/ca IMO, a CA reactor would be second but cost a lot more and requires more maintenance keeping them working properly. 2 part is great for adjusting one of the parameters if there is an imbalance in the tank, or for small tanks, but for larger tanks with hard corals 2 part does get expensive when compared to kalkwasser.

I have been doing Kalkwasser and 2 part. With my 75 gallon I just added what the directions told me for kalkwasser and just changed the 2 part to a lower dose each day. Is kalkwasser suppose to be instead of 2 part?

It depends on what is growing in the tank. If you have a large tank full of hard corals it is possible to dose Kalkwasser in your top off water and still fall short of maintaining Alk/CA. There is a limit to how much Kalkwasser can maintain those 2 parameters. Adding vinegar to the mix does give Kalkwasser more power but even with that it can fall short in some cases. I have seen many large tanks (200G+) that have a dedicated Kalkwasser reactor sitting next to a Calcium Reactor because either one by themselves can't keep up with the tanks demands. Kalkwasser adds both Alkalinity and Calcium at the correct ratios. So if the goal is to try and bump one parameter up but keep the other the same then that is where 2 part comes in, or if Kalkwasser by itself isn't able to maintain the parameters you can do both kalk and 2 part.