plants with yellow stem

[augi_ow]

just started this hobby, but i notice my plants wither very easily...
it starts with the stem just above the root starts to turn yellow, then the stem becomes weak, then the whole plant just break off and floats to the surface... i don't really know what nutrient the plant is lacking...

my tank specifics are

2L CO2 cylinder...being injected with diffuser

1 x 36W PL lighting and 1 X 15w FL lighting

using rena xp 1 external filter... output valve switch to the lowest

1 teaspoon of liquid fertiliser added everyday...

base fert.. don't really know what brand is it... but the packaging is in a white tub form....

my ph is 6.3 kh is 3 Co2 is 1bps

[CT]

maybe you can provide us with more info like the size of your tank, what is the brand of the liquid fertilizer, the plant you are talking about.

I presume your tank is 2ft. The stem just above the roots starts to turn yellow, I think maybe the part of the plant above it is too dense and light was unable to reach the bottom part.