I recently bought a fluval u1 filter but it doesnt have carbon filter foams like my old filter that i got with the tank. Is it normal for a filter just to have one foam?
A lot of small filters have only one sponge. You don't actually need the carbon sponges, just the one sponge is fine. With my small filters, I cut the sponge in two so I can wash half at a time.
So long as the filter outflow is rippling the surface of the water, it doesn't matter if the bubbles from the filter have stopped working. My filters don't make bubbles, and I don't have an air pump either.