Grassbed Tank biotope(need help with bed)

[Bluetangclan]

I am building a grassbed tank, going to use turtle and shoal grass along with some attractive macro with a small rock shoal in the center built based on pvc pipe.
I plan on having a 5 inch or so sand bed. I am not entirely sure I want it all to be sand. In the search function theres mention in a four year old thread of using flourite or something else on the bottom layer as fertilizer. Having limited experience with gardening, should I do the whole thing sand or put a plant encouraging layer under the sand? Seeing as its four years after the thread and no results were posted, what should I use?

 

[jasonrp104]

I don't know too much about them but there's a few really nice ones in the macro forum

 

[Bluetangclan]

Woooops didnt know we had a macro forum on here. Great, another place to haunt.

 

[jasonrp104]

http://www.reefcentral.com/forums/showthread.php?t=1660630

here's one 4 ya

 

[billsreef]

Those grasses like a fairly organic rich substrate, i.e. dirty sand. Mixing in a little marsh mud or fertilizer free potting soil into the lower levels of the bed can be helpful.

 

[uhuru]

how about something like miracle mud?