This is my first attempt at a lager. I have several ales under my belt that turned out great. First off, I cold pitched a tube of German Lager WLP830 with no starter on 6-20-09. After a few days of watching no fermentation starting and reading on the internet, I realized I under pitched severely. No worries, I headed to the brew shop, they were out of WLP 830, so I bought the German Bock strain WLP 833, and made a 1 liter starter. I pitched the starter, and removed the carboy from the refrigerator. After the warm up to about 68 degrees F, and signs of fermentation started, I placed the carboy back into the refrigerator and brought temp down to 50f. It fermented for about a week with visible signs of activity. Now the yeast has seemed to have slowed down. My OG was 1.041, and my reading the last two days has been 1.018. Should I give a lager more time before comparing readings, or is it safe to say that I did not pitch enough yeast, and the primary phase is complete? Or should I just relax and let it go another week, and take another hydro reading then? I am not familiar enough with lager fermentation to know if the bottom fermenting yeasties are working at such a slow rate that I can not see signs of active fermentation. There were quite a bit of carbonation bubbles from in my sample. Is this a sign of active fermentation?