Good to hear your fish survived. Yes, your skimmer should have bubbles. LOTS of bubbles, as this is what pulls the particulate out of the water. Some may have different opinions, but I've found that smaller bubbles in high volume will remove more than lots of large bubbles. You will have to adjust the water level to about 1 1/2 - 2 inches from the top of the tube. With a little practice, you will be able to distinguish where the water level becomes separate from just bubbles. The bubbles should not reach the top of the tube until they start taking on a brown tint. If clear, white bubbles are reaching the top and the water in the collection cup is light brown, lower the water level just a touch. Darker is better, because you're removing more particulate without taking any more water than necessary. It may take a day or two (or more) to dial it in, but once you find that sweet spot it'll be easier to find it afterwards. The key to skimmer efficiency is to tune it to the max, and keep it CLEAN. The top of the tube will become coated with gook, and this will lessen it's effectiveness. I think many will agree that cleaning the tube and collection cup twice a week is the norm.