im sorry contra but LR Rubble in the back in the chambers is a bad MAJOR idea. It will collect detritus which will become Nitrates which we dont want that. just add chaetomorpha thats the most important part. you already have LR in the DT so no need in having it in the back. For the koralia nano i would get a koralia 1. i would also buy the Sunpod 70w HQI for the tank if you wanna do sps and have better lighting system.
for return pump i would replace it with a maxi-jet 900 or 1200. or spanko might let you know on a rio thats good.
here read this for the chambers:
First you will notice in the back of your tank you will have three chambers. In the 1st you will have a big sponge, 2nd small sponge, bag of ceramic rings, carbon and bio balls. 3rd you got your pump.
Now to start off i want you to take everything out of chambers 1 & 2. Dont touch 3.
Next i would like you to go to LFS or search online for these items.
Chemi-pure
Purigen
Chaeto
Fliter Floss
Small Light.
In Chamber one you will want to put in the Chemi-pure, Purigen and Filter Floss. The Filter Floss is optional, if you do use it i would replace every week or two, depends on how dirty it get.
Chamber two Is where you put the Cheato and light. The best way for it, is to add the Cheato in a cup. Keeps back area a bit cleaner. Now for the light i have an AZOO PALM LIGHT Cant post links, but google it and you will find it.