Just had our first flat on our new bike.

Though I have resisted in the past - on some of my other bikes, I have tried slime tubes and so far, I'm pretty impressed. I used to have to check the tires for every ride, now I find that I rarely have to add air. I'm thinking of going to slime tubes for the tandem. I realize that it adds some weight but it seems like it could avoid some hassle. Any opinions?

Also, on our old tandem, we carried a frame pump. On the new bike we're carrying a CO2 inflator. When we had the most recent flat, I used the cartridge that came with the inflator. I think it was a 16gm cartridge. In the past I've only used 12gm cartridges. I was pretty careful and wasted very little of the cartridge but it seemed like the 16gm underfilled the 700x25 tire (didn't have a gauge). Does anyone know if a 12gm is too little or if a 16gm is too much for a 700x25 tire?