[Wrassman]

[glow=Teal, 2, 90%]Kalkwasser would be a good way to increase alkalinity in the tank. Of course, it will probably also raise your pH. Baking Soda (sodium bicarbonate) will raise your alkalinity as well, and it will have a negative impact on your pH level (it will lower it) What would be ideal is a Calcium Reactor, which would raise your Ca level and put CO₂ into the tank, lowering your pH in the process.

For the time being, if you are still interested, add some baking soda and bring up your Alk. This will have the net effect of lowering your pH.

We still don't know what your Ca is, though. But, if you can't maintain Alk or pH, you aren't going to be able to maintain any kind of decent Ca level for very long.

I have at least 12 links to great articles concerning Ca, Alk, and pH in the aquarium. If you are interested in pursuing this in depth, let me know, and I will share some of the links in this thread...[/glow]