Chris, I was thinking about your refill and it seems like your tank didn't last very long. I just got mine refilled but I didn't start with a full tank. You don't have that many SPSs that you would go through a tank in only around 6 weeks - JMO. Maybe we need to get an average refill time, like The Hawk'ster - how long does your CO2 tank last for your 90G? I thought something like 3 months for the 5# but I could be way off here.