I work for a tavern that has 2 3100 gallon tanks. They were installed 6 weeks ago and the maintenance guy scheduled them to be pumped about every 3 weeks. That seems quite excessive to me. Any thoughts on this issue. I thought we could go for about 6 months. It has an alarm system and I believe the alarm sounds when there is about 500 - 1000 gallons remaining - is this correct?