Planted Tank Guru
Join Date: Jan 2010
Location: Contra Costa CA
Plants need over a dozen elements to live.
Many of these are supplied in the water and fish food.
Some are in short supply in these sources, or else the tank has a lot more light, so the plants need more fertilizers than are supplied that way.
The fertilizer program needs to be geared toward supplying what the tank is low in.
Can you tell us more about the tank and the water parameters?
What kind of light? including the name and type of bulbs.
How long you run them.
Tank size and shape.
Water test results for both tap (if that is how you fill the tank) and the tank (right before a water change):
ammonia, nitrite, nitrate, GH, KH, pH and any other test results you have.