Hi all,
Welcome to the forum.You just need a fertiliser that supplies all the macro and micro-nutrient requirements for your plants.
<"Telanthera" cardinalis> has quite a high CO2 demand, so you may need to supplement the carbon. I'm not a high tech. plant keeper, so others may be able to tell you how easy it is to grow without added carbon.
An "all in one" fertiliser mix might be your best option, have a look at this post <"
All-in-One ...">.
How much/often you add fertiliser depends upon a number of factors, I use the
<"health of a floating plant"> ("Duckweed Index") as a visual indicator of when fertiliser is needed, others use a weekly addition.
cheers Darrel