i dont see any heater....
and didnt you said your going to put in white sand???
btw what kind of filter do you have???
i have quite flow 10 and i found out that the filter's downside is super slow to culture good bacteria in it. check your filter if theres any place for good bacteria to live in. if theres not, customize your filter and add in sponge next to your bio cartridge (preffereably white sponge/cotton) and when the sponge turned brown that means good bacteria is growing there.
heres the thread http://www.bettafish.com/showthread.php?t=57017