i have a fluval u2 filter in my 60l tank. ive had it running about a month,how often shud i clean it all out inside filter, i know to clean it in tank water,not tap water, also i took my pump out of the tank,and using the top outlet of the filter for air bubbles in tank, is that okay? i have the fluval u23 filter so the water comes out the top,at full flow,is that the right setting. im new to this fish keeping so kn ow little, thanks