The Fluval AquaClear 30 Power Filter is a hang-on-the-back power filter for aquariums of 38 to 114 litres, running mechanical, chemical and biological media in one basket.

Key Features

• Hangs on the back rim of the tank, so it takes up no space inside and everything is reachable without getting wet
• Three media stages in one basket: foam for debris, activated carbon for dissolved organics, and BIOMAX ceramic rings for the bacteria
• Refiltration system — some of the water is passed through the media more than once, which gives longer contact time than a single pass
• Adjustable flow control, so the output can be turned down for small or long-finned fish
• All media supplied with the filter
• For use in both freshwater and saltwater aquariums
• Made by Fluval, the aquatics brand of Rolf C. Hagen, which has been building aquarium filters since 1975

Setting It Up

• Hang it on the back rim, fill the chamber with tank water to prime it, then switch it on. Running it dry will damage the impeller
• Leave a little clearance behind the tank for the body of the filter
• A new tank has no bacteria in it. Cycling — running the filter for several weeks until it processes ammonia and nitrite to zero — has to happen before fish go in, or they sit in their own waste while the bacteria catch up
• No filter is silent. Most of the noise people complain about is air trapped in the impeller housing or a unit that is not sitting level

Maintenance

• Never wash biological media in tap water and never replace it all at once. Chlorine kills the bacteria living on it, and changing everything together restarts the cycle
• Rinse mechanical foam in a bucket of old tank water rather than under the tap
• Change the carbon monthly. Carbon becomes exhausted rather than dirty, and spent carbon does nothing
• Replace only part of the BIOMAX at a time, so the bacterial population survives
• Unplug anything electrical before putting your hands in the tank
• A liquid test kit for ammonia, nitrite and nitrate tells you more about a tank than anything you can see

Good To Know

• Superseded by the Fluval AC30, which Fluval lists as the direct replacement for this model
• Hang-on filters need the water level kept up. Let it drop and the return splashes, which is noisy and gases off CO2 in a planted tank
• The outflow is a waterfall. That suits most community tanks but is too much current for a betta or a long-finned fancy goldfish
• Most tanks want 20–30% of the water changed weekly, with the replacement dechlorinated and matched for temperature