Unless your aquarium is outfitted with an air stone you should not see bubbles in the aquarium. Water has probably evaporated from the system and it is important that it be refilled. You should maintain a water level that is about half way up the filter at all times. You can add purified water right to the filter. If you have any questions just give us a call.
About Jon Wolf
Servicing Illinois, Wisconsin, Indiana & Michigan, Blue Planet Aquarium Services has been the most trusted name in aquarium design, installation and maintenance since 1999. A company large enough to be dependable but small enough to still watch out for your best interests, Blue Planet is the only company to call if you are planning to install an aquarium or have one maintained.