Using a PH buffer is usually not a good idea. At the very least, you'll want to carefully monitor your alkalinity. If you have a reef tank, some PH buffers have chemicals that are not very conducive to a healthy reef. Kalkwasser drip is a good way to bring up PH, but as low as yours is, you have some other issues. First, how are you testing your PH? Are you using a test kit or probe, and which brand? You may very well be getting a bad reading, so you may want to get it tested by someone else first. Now, a few other questions:
1) Is your tank covered? Glass covers limit gas exchange and allow CO2 to build up, which will lower PH.
2) Do you have a lot of people in the house and are the doors and windows usually closed? PH often times drops in the winter, because there's a buildup of CO2 inside the house since the doors and windows are usually closed.
3) What do you have for water circulation? Without sufficient water circulation including disturbing the surface of the water, gas exchange is limited and CO2 builds up.
Dripping kalk is fairly easy to do, but before you do, it would be best to get to the root of your problem.