First time community tank

[Liberty]

Hi guys,

I'm looking at changing my set up a little bit and want to get some South American fish in place of my remaining (and more aggressive) African cichlids.

A couple of questions I have;

• Do I need to change the substrate? I currently have small browny-coloured pebble-like substrate. Is this similar to what is found in their natural habitats?
• Is there much of a change required in the way of filtration, water circulation, decorations and overall tank maintenance? I currently have an Aqua One AquaStyle 620 - 90L curved glass aquarium with a Nautilus 600 canister filter (I have had this for a number of years now and I'm thinking it's on its way out, it doesn't seem to be as strong from the outlet as it used to be). I have changed the seal and impeller but there is no change. A replacement pumphead is about $125; I may as well buy a new canister filter than simply replacing the pumphead for the exact same price.
• I am looking at making the tank as near to their natural environment as possible. What are some live plants you would recommend for such a set up?
• I am a huge fan of Cardinal Tetras so a small school of them are a must for me. What other fish would do well with this species?

I may have some more questions but they're the ones that come to mind at the moment.

Thanks for your help guys.

[Skippy]

If you like the look of the substrate you already have then there is no need to change it.  South America is pretty big so there are a wide variety of biotopes present including ones with gravel substrate.  If you are going for a natural look, the hard scape and plants are probably more important than the substrate.

The internet recommends over stocking African cichlids tanks to cut down on aggression which leads the internet to recommend "over filtering" and big water changes for African cichlid tanks.  Your 600 lph filter turns over the 90 litres of water a little more than 6 times an hour.  Considering many filters rate their LPH with no media inside and you think that output is a bit reduced your current filter is probably going to be fine for a South American community tank.  Depending on what type of fish you end up with will determine if you have too much current.  You can always direct the canister outflow towards the glass or put on a spray bar if you are keeping some fish that don't like the flow. 

Amazon swords are an easy to grow plant that fits your desired South American look (make sure you choose a species that won't get too big for your tank).  Anubias, java fern are easy to grow plants that attach to rocks or driftwood but aren't strictly speaking South American plants.  Vallisneria also grows well in most community tanks but again this isn't a strictly South American species.

IMO, Cardinal tetras and all tetra species look best in big shoals, other tetras would do well with them, Apistogramma and other dwarf cichlid species would probably be ok too.