Regardless of species, as hard corals grow, they consume more and more calcium carbonate from the water. It’s vital that the water housing corals has enough calcium available, along with the correct measure of carbonate hardness. Without this, corals cannot properly grow and a healthy reef cannot properly form. If you have a successful reef, in that you’ve maintained the right balance of calcium, carbonate hardness and magnesium, sooner or later your ph will start to fall. The animals will be using calcium and carbonate from the water, and this will in turn lower the ph. There are a host of chemical processes that explain this, but that’s more fodder for something written by Randy-Holmes Farley. Simple fact, your ph will start to drop lower, even though your alkalinity measures at or around 8-10 dKH. Many aquarists wonder why this is happening, and to correct it, they turn to carbon dioxide air reactors or more powerful skimmers. As a Band-Aid, these work for a while. CO2 reactors pull co2 out of the air entering the skimmer, and the oxygen-rich air helps dilute some of the tank’s co2, raising ph. You may see the ph increase a few points here or there, but in all likelihood it will drop back down with time. A powerful skimmer will inject more air and create more turbidity, and like a co2 reactor, may temporarily raise the ph a few notches. As an aquarist, you really don’t have many options to correct this issue. You could dose like it’s nobodies’ business, but in the end that will lead to swinging ph levels, along with unbalanced calcium and carbonate hardness. Congratulations, as you have a reef that is creating a moderate calcium/carbonate demand, which means it’s growing. Now, you have to find a stable way to meet that demand. Of all the options out there, a kalkwasser stirrer may be the easiest, and most cost effective. Ph swings and calcium demand:
There are multiple ways to increase both the alkalinity and calcium value of reef aquarium water. Some are as simple as baking soda, while others implement a three-part additive. These can be dosed manually, and tailored to water test results, or they can be automated if things remain consistently stable. The short-coming is that the water chemistry in a reef aquarium changes. Corals begin growing, their demand on calcium may increase, or corals are added, fragged, etc.… More:
The post Kalkwasser: An oldie but goodie. appeared first on Reefs.com.