Originally Posted by o.jonathan.o
Try this one out.
Aqueon Aquarium Power Filters at PETCO
They have different sizes and the smallest being rated 5-20 so it may be a little much. Internal filters are pretty cool just not the air driven ones
thats about the same size as a aquaclear 20.
for a tank that small a sponge filter will be ur best bet.
there r smaller HOB
filter but i wouldnt bother buying one.
a DIY sponge filter with filter floss will work.