Compression? Images recorded from Camera are too big.

[m33ksauce]

I'm new to Zoneminder, and I've been experimenting with using it for primary storage of our recorded camera feeds. The problem, though, is that 10 minutes of recorded frames amount to over a gig of data. Our current system uses less than 100 megs and records for approximately 3 months. We're moving everything to a much larger hard drive, but at over 800GB per day for our 6 cameras, we won't even get 24 hours out of it. Can anybody help me?