Moss, nana & fern not require CO2
but of cos the growth rate & pattern will b different
if u hv good light, fert no need to replace the sand...
some plant can grow on it, glosso, hair grass, streuogyne
just put some substrate in it e.g ISTA "jagung" fertilizer, ADA iron bottom, BW ?? (cant recall the name)
the only thing u hv to be patience
if u hv time u can visit aquaworld at damansara damai
YT's 6ft display tank, run more then 3yrs with sand...which can grow different plants
Yes plants can grow on sand provided that you dose complete set of nutrient to them through all kinds of ferts.
Those fertilizers doesnt come cheap. Eg: 2bottles of BW already cost Rm110.