I just purchased 2 liters (2000 mil) of Pond Prime for $47 which includes shipping and treats 40,000 gallons or 5 mil/1 cap treats 100 gallons. This compared to regular Prime which cost about $58 for 2 liters with shipping and treats only 20,000 gallons or 5 mil/1 cap treats 50 gallons. Is this a no brainer deal since both are the same only one is twice the strength and cost less due to marketing?