AquaClear Inserts push up from the filter
 
 

Actual Problem: The left side of the lid on the filter keeps popping up causing noise. The filter material wants to rise and there seems to be nothing to lock it in. On the right hand side there is a tab that the plastic insert locks into but I can't get it to lock into anything on the left side. This in turn allows the plastic insert holder rise up, lifting the cover off.
Aquarium Size: 33
Aquarium Age: 24
Type of fish: African cichilids
Number of fish: 8
Last water change: weekly
Percent changed: 30%
Primary Filtration System: Aquaclear 300
Secondary Filtration System: na
Last Media Change: last month

The reason that a filter will have the media push up is because the foam or other media is often so dirty it creates more resistance than the tab on the impeller well can tolerate. In essence this is a warning that it is time to replace or rinse the filter materials. Often this will be a sign that the foam, which is oversized for the actual compartment slightly, has filled and causing too much resistance. It must be at least rinsed, but if it is older and you are rinsing it often, then this is a sign that the holding capacity has been filled, and that it should be replaced with a new foam.

The rising is just like a safety valve, when pressure in a system rises too high, something has to give, and the AquaClear uses the rising media basket as a sign that the filter is overdue for a cleaning. I must hasten to add that you should never replace all the filter media at once, if you do change the foam, rinse the carbon out well in used aquarium water to conserve the beneficial bacteria that are removing the ammonia and nitrite from your aquarium. Once it has been rinsed thoroughly in dechlorinated water (chlorine or chloramine will kill the bacteria it takes so long to grow) replace it into the filter. Wait at least a week or two before replacing it with a new insert to allow the chance for the new foam to be seeded.

The foam is much longer lived that the carbon and can be rinsed during every filter maintenance that the carbon is removed. Just be sure that the water you rinse is from a regular water change so it is safe to the bacterial populations - we term this multiple insert conservation of bacteria the CycleGuard system.

Hope that answers your questions about the cause and the fix of "rising filter media" in the AquaClear system.