I’m currently dosing evolution aqua complete fertiliser daily 1ml a day in 9 gallon tank
Does the bottle say anything about what it contains percentage wise of nutrients?
It if doesnt then im afraid this is another one of the fertilizers where we wont be able to advise super accurately on the dosage amount, because we dont know the actual contents of it.
It just makes me wonder because Hydrocotyle Tripartita grows really well and start to take over more space now.
Based on your tank picture (thank you for including it😊) I would say your tank has somewhat low plant mass. Your tank is quite tall and a lot of the volume of the tank is not occupied by plants.
Youre injecting CO2 though so your plants will be growing faster than they would in a non CO2 tank, so will inherently need more food than a non CO2 tank.
From their website (mostly to save the other people reading this thread from looking it up)
Low - aquariums with low lighting and no CO2 or liquid carbon
Med - aquariums with low-moderate lighting and liquid carbon
High - aquariums with moderate-high lighting and CO2 gas injection.
Dosage Guidelines
Low - 1ml per day per 50 litres
Med - 2ml per day per 50 litres
High - 5ml per day per 50 litres
*Dosage assumes high plant biomass.
I think based on the total picture your current dosing doesnt sound particularly off to me, others might chime in as well with what they think.
It is CO2 injected but it has low plant mass, so I dont think it should get the high dosing right off the bat.
You could try 2ml per day if you want to, theres no harm in experimenting a bit and getting a feel for what your tank needs.
Are you observing any problems with the plants? If so, are the problems located in the oldest parts of the plant or the newest parts?
In a tank which is this tall, I would pay extra close attention to CO2 distribution, especially along the bottom of the tank, as the gas may have a hard time getting distributed evenly all the way.