Note for comparison with the "EHEIM biopower":
Well logically attracts the "biopower" "only" on the lower chamber of the water, because it loudly EHEIM like a (canister) external filter is constructed so and so also to act - a (canister) external filter specifically from EHEIM and also other manufacturers leads the water yes in principle "only" from below through all filter layers. In this respect are "aquaball" and "biopower" neither better nor worse, but simply just different in their functioning.
That such internal filter "frequently" (a relative term) must be cleaned, is partly, of course, to their compactness and on the other hand - as with all filters - even at the individually different conditions in each aquarium (stocking and feeding - both often too much -, plant selection, water quality, etc.). I control my filter 1x monthly and clean it, so the filter media hausptsächlich, then finished also, if necessary, so no great effort and quickly. Rather clean the filter media a little less than too much. In a biologically established aquarium filter system really need to only be cleaned when the filter performance (better flow capacity, visible at the water outlet) has declined significantly.
