Interesting. Although not exact, most people get about 3+ months on a 5lb cylider at 1 bubble per second. If you last only a week, that is 12-4 bubbles or so per second. Not even sure you can diffuse that rate in an active reactor or push that much through a normal glass frit without creating a massive bubble storm.
While I completely agree that a sump will increase CO2 loss, I still question whether you had a leak before the reactor.