Shilala Beads

I went to go check out a humidor today that i found on CL and bought it. The dimensions are; L- 24"xW-24"xH-30". After doing the calculations for Shilala beads it says I need; 17280 cu.in. or 2 lb. The humidor is supposed to hold 2000 sticks but I'll only have about 200 loose and 4-5 boxes in there for now. Do i need to actually purchase 2 lb or can I do with less for now?

The current owner uses the old green foam, and it holds temp and rh at 70/67%. I checked his hygrometer and the min/max in memory was 63/72. Any help would be great, I've never had to deal with a humi this big but he made me an offer I just couldn't turn down.

**If this is the wrong place to post this apologies