stocking? :)

hi guys so along the road of aquariums i have learnt a lot from fish deaths to sitting back and watching a thriving aqaurium so on the end of my construction for the tank i was wondering if by adding about 6 more tetras and one more peppered cory? at the moment i have 6 corys (4 bronze and 2 peppered ) 6 glowlight tetras and 2 golden eye dwarf cichlids. please let the suggestions flow

 

its all about the frequency of water changes for me.
I'm keeping 20 tetras happy in a 3 foot and in that same tank before them 300 angles.
the tetras are happy with 1 small water change a week where the angels "demanded" 2 changes a day.

 

well i do a change almost every 3 days cause of all the waste from the food of the corys and also got a lot of roots floating around from plants i added a while ago so still combating the breakdown of that etc

 

@KennyG How big is your tank?