just get a simple tank,add a hang-on filter and maybe a skimmer and let it run not forgetting fortnightly water changes,simple and neat jus like the nano tank at iwarna's counter
get RO units or better still get those water filters tat is used to filter our drinking water like those manufactured by Osim and Diamond....
One word of caution RO units wastes a lot of water....
Wah,u want to buy bottled distilled water to change water...I salute u