This guy was spot on until 1:10, the filter does
aerate the water. Granted the bacteria need O2
, they are not going to suck all of the oxygen out of the water. He actually contradicts himself because he says that you have to have surface agitation to provide for gas exchange. Then he turns around and acts like your filter doesn't aerate. Filters produce surface agitation and thus provide for gas exchange just like an airstone. So, really , an airstone is not required although since he was talking about Cichlids it is always better to have too much aeration. Especially since they almost always are in overstocked tanks. However, for the average Joe tropical aquariust an airstone is just aesthetics or maybe for emergencies.