The thing about externals is that they have a lot more space for media, than most other filters. Also, they are made to use biomedia, so cleaning of pre-filter and polishing sponge is much easier.
The spray bar is usually half a centimetre underwater, it gives your more surface agitation and better circulation. I would definitely use one over not using one.
The spray bar is usually half a centimetre underwater, it gives your more surface agitation and better circulation. I would definitely use one over not using one.