stem issue

so ive had my tank up and running for a few months and ive recently begun having a problem with stems decaying at them bottom and breaking away. im not sure as to waht could be the problem. ill give my tank specs and lets see if anyone can shed light


29 gal
1.3 watts per gal and indirect light from windows
ph 6.8
temp 78
gh 4
kh 3.5
nitrates- 0-5 ppm depending on my nitrogen dose
flourite base
co2 injection ( which ran out recently and havebeen supplementing excel till i get it filled)

plants
hornwort
red tiger lotus ( which is thriving the most strangely)
rotala indica
green hygro
banna plant
bacopa
wenditii crypts

fish
3 dwarf apistos
3 ottos
3 kuhli
3 cories
5 rasbora
1 hillstream loach
couple amano shrimp

ferts
kents freshwater plant for micros
flourish nitrogen
flourish potassium
flourish excel

i think im missing phosphates but havnt been able to find flourish phospate or enema stuff. hmmm i should get a plant test kit today mabye.

only 2 theories i have are to low of light, and no phosphate.

anyone else?

green hygro seems to have a bit of a problem. rotala indica seems ok but still some of the stems dont look so hot. 1.3 is low but its like a hundred bucks to get it up to 2 watts per gallon and thats a pretty big chunk of cash.

i pull em apart seperatly, which is a pain i the *** with small stems like the rotala. i guess ill find out if its light as today i went and bought a 55w power compact. so with that one and another 20w strip im pushing 2.5w per gal now. should be enough